diff --git a/src/python_testing/TC_MCORE_FS_1_2.py b/src/python_testing/TC_MCORE_FS_1_2.py
index 1085b0fac0a07c..c199225b33f99c 100644
--- a/src/python_testing/TC_MCORE_FS_1_2.py
+++ b/src/python_testing/TC_MCORE_FS_1_2.py
@@ -19,27 +19,102 @@
 # for details about the block below.
 #
 
-import base64
+import hashlib
 import logging
+import os
 import queue
+import secrets
+import signal
+import struct
+import subprocess
 import time
+import uuid
+from dataclasses import dataclass
 
 import chip.clusters as Clusters
 from chip import ChipDeviceCtrl
-from matter_testing_support import MatterBaseTest, TestStep, async_test_body, default_matter_test_main
+from ecdsa.curves import NIST256p
+from matter_testing_support import MatterBaseTest, TestStep, async_test_body, default_matter_test_main, type_matches
 from mobly import asserts
 from TC_SC_3_6 import AttributeChangeAccumulator
 
+# Length of `w0s` and `w1s` elements
+WS_LENGTH = NIST256p.baselen + 8
+
+
+def _generate_verifier(passcode: int, salt: bytes, iterations: int) -> bytes:
+    ws = hashlib.pbkdf2_hmac('sha256', struct.pack('<I', passcode), salt, iterations, WS_LENGTH * 2)
+    w0 = int.from_bytes(ws[:WS_LENGTH], byteorder='big') % NIST256p.order
+    w1 = int.from_bytes(ws[WS_LENGTH:], byteorder='big') % NIST256p.order
+    L = NIST256p.generator * w1
+
+    return w0.to_bytes(NIST256p.baselen, byteorder='big') + L.to_bytes('uncompressed')
+
+
+@dataclass
+class _SetupParamters:
+    setup_qr_code: str
+    manual_code: int
+    discriminator: int
+    passcode: int
+
 
 class TC_MCORE_FS_1_2(MatterBaseTest):
+    @async_test_body
+    async def setup_class(self):
+        super().setup_class()
+        self._app_th_server_process = None
+        self._th_server_kvs = None
+
+    def teardown_class(self):
+        if self._app_th_server_process is not None:
+            logging.warning("Stopping app with SIGTERM")
+            self._app_th_server_process.send_signal(signal.SIGTERM.value)
+            self._app_th_server_process.wait()
+
+        if self._th_server_kvs is not None:
+            os.remove(self._th_server_kvs)
+        super().teardown_class()
+
+    async def _create_th_server(self, port):
+        # These are default testing values
+        setup_params = _SetupParamters(setup_qr_code="MT:-24J0AFN00KA0648G00",
+                                       manual_code=34970112332, discriminator=3840, passcode=20202021)
+        kvs = f'kvs_{str(uuid.uuid4())}'
+
+        cmd = [self._th_server_app_path]
+        cmd.extend(['--secured-device-port', str(port)])
+        cmd.extend(['--discriminator', str(setup_params.discriminator)])
+        cmd.extend(['--passcode', str(setup_params.passcode)])
+        cmd.extend(['--KVS', kvs])
+
+        # TODO: Determine if we want these logs cooked or pushed to somewhere else
+        logging.info("Starting TH_SERVER")
+        self._app_th_server_process = subprocess.Popen(cmd)
+        self._th_server_kvs = kvs
+        logging.info("Started TH_SERVER")
+        time.sleep(3)
+        return setup_params
+
+    def _ask_for_vendor_commissioning_ux_operation(self, setup_params: _SetupParamters):
+        self.wait_for_user_input(
+            prompt_msg=f"Using the DUT vendor's provided interface, commission the ICD device using the following parameters:\n"
+            f"- discriminator: {setup_params.discriminator}\n"
+            f"- setupPinCode: {setup_params.passcode}\n"
+            f"- setupQRCode: {setup_params.setup_qr_code}\n"
+            f"- setupManualcode: {setup_params.manual_code}\n"
+            f"If using FabricSync Admin test app, you may type:\n"
+            f">>> pairing onnetwork 111 {setup_params.passcode}")
+
     def steps_TC_MCORE_FS_1_2(self) -> list[TestStep]:
-        steps = [TestStep(1, "TH_FSA subscribes to all the Bridged Device Basic Information clusters provided by DUT_FSA to identify the presence of a Bridged Node endpoint with a UniqueID matching the UniqueID provided by the BasicInformationCluster of the TH_SED_DUT."),
-                 TestStep(2, "TH_FSA initiates commissioning of TH_SED_DUT by sending the OpenCommissioningWindow command to the Administrator Commissioning Cluster on the endpoint with the uniqueID matching that of TH_SED_DUT."),
-                 TestStep(3, "TH_FSA completes commissioning of TH_SED_DUT using the Enhanced Commissioning Method."),
-                 TestStep(4, "Commission TH_SED_L onto DUT_FSA’s fabric using the manufacturer specified mechanism."),
-                 TestStep(5, "TH_FSA waits for subscription report from a the Bridged Device Basic Information clusters provided by DUT_FSA to identify the presence of a Bridged Node endpoint with a UniqueID matching the UniqueID provided by the BasicInformationCluster of the TH_SED_L."),
-                 TestStep(6, "TH_FSA initiates commissions of TH_SED_L by sending the OpenCommissioningWindow command to the Administrator Commissioning Cluster on the endpoint with the uniqueID matching that of TH_SED_L."),
-                 TestStep(7, "TH_FSA completes commissioning of TH_SED_L using the Enhanced Commissioning Method.")]
+        steps = [TestStep(1, "TH subscribes to PartsList attribute of the Descriptor cluster of DUT_FSA endpoint 0."),
+                 TestStep(2, "Follow manufacturer provided instructions to have DUT_FSA commission TH_SERVER"),
+                 TestStep(3, "TH waits up to 30 seconds for subscription report from the PartsList attribute of the Descriptor to contain new endpoint"),
+
+                 TestStep(4, "TH uses DUT to open commissioning window to TH_SERVER"),
+                 TestStep(5, "TH commissions TH_SERVER"),
+                 TestStep(6, "TH reads all attributes in Basic Information cluster from TH_SERVER directly"),
+                 TestStep(7, "TH reads all attributes in the Bridged Device Basic Information cluster on new endpoint identified in step 3 from the DUT_FSA")]
         return steps
 
     @property
@@ -49,16 +124,21 @@ def default_timeout(self) -> int:
     @async_test_body
     async def test_TC_MCORE_FS_1_2(self):
         self.is_ci = self.check_pics('PICS_SDK_CI_ONLY')
+
         min_report_interval_sec = self.user_params.get("min_report_interval_sec", 0)
-        max_report_interval_sec = self.user_params.get("max_report_interval_sec", 2)
-        report_waiting_timeout_delay_sec = self.user_params.get("report_waiting_timeout_delay_sec", 10)
+        max_report_interval_sec = self.user_params.get("max_report_interval_sec", 30)
+        th_server_port = self.user_params.get("th_server_port", 5543)
+        self._th_server_app_path = self.user_params.get("th_server_app_path", None)
+        if not self._th_server_app_path:
+            asserts.fail('This test requires a TH_SERVER app. Specify app path with --string-arg th_server_app_path:<path_to_app>')
+        if not os.path.exists(self._th_server_app_path):
+            asserts.fail(f'The path {self._th_server_app_path} does not exist')
 
         self.step(1)
-
-        # Subscribe to the UniqueIDs
-        unique_id_queue = queue.Queue()
+        # Subscribe to the PartsList
+        root_endpoint = 0
         subscription_contents = [
-            (Clusters.BridgedDeviceBasicInformation.Attributes.UniqueID)  # On all endpoints
+            (root_endpoint, Clusters.Descriptor.Attributes.PartsList)
         ]
         sub = await self.default_controller.ReadAttribute(
             nodeid=self.dut_node_id,
@@ -66,82 +146,38 @@ async def test_TC_MCORE_FS_1_2(self):
             reportInterval=(min_report_interval_sec, max_report_interval_sec),
             keepSubscriptions=False
         )
+
+        parts_list_queue = queue.Queue()
         attribute_handler = AttributeChangeAccumulator(
-            name=self.default_controller.name, expected_attribute=Clusters.BridgedDeviceBasicInformation.Attributes.UniqueID, output=unique_id_queue)
+            name=self.default_controller.name, expected_attribute=Clusters.Descriptor.Attributes.PartsList, output=parts_list_queue)
         sub.SetAttributeUpdateCallback(attribute_handler)
+        cached_attributes = sub.GetAttributes()
+        step_1_dut_parts_list = cached_attributes[root_endpoint][Clusters.Descriptor][Clusters.Descriptor.Attributes.PartsList]
 
-        logging.info("Waiting for First BridgedDeviceBasicInformation.")
-        start_time = time.time()
-        elapsed = 0
-        time_remaining = report_waiting_timeout_delay_sec
-
-        th_sed_dut_bdbi_endpoint = -1
-        th_sed_dut_unique_id = -1
-
-        while time_remaining > 0 and th_sed_dut_bdbi_endpoint < 0:
-            try:
-                item = unique_id_queue.get(block=True, timeout=time_remaining)
-                endpoint, attribute, value = item['endpoint'], item['attribute'], item['value']
-
-                # Record arrival of an expected subscription change when seen
-                if attribute == Clusters.BridgedDeviceBasicInformation.Attributes.UniqueID:
-                    th_sed_dut_bdbi_endpoint = endpoint
-                    th_sed_dut_unique_id = value
-
-            except queue.Empty:
-                # No error, we update timeouts and keep going
-                pass
-
-            elapsed = time.time() - start_time
-            time_remaining = report_waiting_timeout_delay_sec - elapsed
-
-        asserts.assert_greater(th_sed_dut_bdbi_endpoint, 0, "Failed to find any BDBI instances with UniqueID present.")
-        logging.info("Found BDBI with UniqueID (%d) on endpoint %d." % th_sed_dut_unique_id, th_sed_dut_bdbi_endpoint)
+        asserts.assert_true(type_matches(step_1_dut_parts_list, list), "PartsList is expected to be a list")
 
         self.step(2)
-
-        self.sync_passcode = 20202024
-        self.th_sed_dut_discriminator = 2222
-        cmd = Clusters.AdministratorCommissioning.Commands.OpenCommissioningWindow(commissioningTimeout=3*60,
-                                                                                   PAKEPasscodeVerifier=b"+w1qZQR05Zn0bc2LDyNaDAhsrhDS5iRHPTN10+EmNx8E2OpIPC4SjWRDQVOgqcbnXdYMlpiZ168xLBqn1fx9659gGK/7f9Yc6GxpoJH8kwAUYAYyLGsYeEBt1kL6kpXjgA==",
-                                                                                   discriminator=self.th_sed_dut_discriminator,
-                                                                                   iterations=10000, salt=base64.b64encode(bytes('SaltyMcSalterson', 'utf-8')))
-        await self.send_single_cmd(cmd, endpoint=th_sed_dut_bdbi_endpoint, timedRequestTimeoutMs=5000)
-
-        logging.info("Commissioning Window open for TH_SED_DUT.")
+        setup_params = await self._create_th_server(th_server_port)
+        self._ask_for_vendor_commissioning_ux_operation(setup_params)
 
         self.step(3)
-
-        self.th_sed_dut_nodeid = 1111
-        await self.TH_server_controller.CommissionOnNetwork(nodeId=self.th_sed_dut_nodeid, setupPinCode=self.sync_passcode, filterType=ChipDeviceCtrl.DiscoveryFilterType.LONG_DISCRIMINATOR, filter=self.th_sed_dut_discriminator)
-        logging.info("Commissioning TH_SED_DUT complete")
-
-        self.step(4)
-        if not self.is_ci:
-            self.wait_for_user_input(
-                "Commission TH_SED_DUT onto DUT_FSA’s fabric using the manufacturer specified mechanism. (ensure Synchronization is enabled.)")
-        else:
-            logging.info("Stopping after step 3 while running in CI to avoid manual steps.")
-            return
-
-        self.step(5)
-
-        th_sed_later_bdbi_endpoint = -1
-        th_sed_later_unique_id = -1
-        logging.info("Waiting for Second BridgedDeviceBasicInformation.")
+        report_waiting_timeout_delay_sec = 30
+        logging.info("Waiting for update to PartsList.")
         start_time = time.time()
         elapsed = 0
         time_remaining = report_waiting_timeout_delay_sec
 
-        while time_remaining > 0 and th_sed_later_bdbi_endpoint < 0:
+        parts_list_endpoint_count_from_step_1 = len(step_1_dut_parts_list)
+        step_3_dut_parts_list = None
+        while time_remaining > 0:
             try:
-                item = unique_id_queue.get(block=True, timeout=time_remaining)
+                item = parts_list_queue.get(block=True, timeout=time_remaining)
                 endpoint, attribute, value = item['endpoint'], item['attribute'], item['value']
 
                 # Record arrival of an expected subscription change when seen
-                if attribute == Clusters.BridgedDeviceBasicInformation.Attributes.UniqueID and endpoint != th_sed_dut_bdbi_endpoint and th_sed_later_unique_id != th_sed_dut_unique_id:
-                    th_sed_later_bdbi_endpoint = endpoint
-                    th_sed_later_unique_id = value
+                if endpoint == root_endpoint and attribute == Clusters.Descriptor.Attributes.PartsList and len(value) > parts_list_endpoint_count_from_step_1:
+                    step_3_dut_parts_list = value
+                    break
 
             except queue.Empty:
                 # No error, we update timeouts and keep going
@@ -150,26 +186,63 @@ async def test_TC_MCORE_FS_1_2(self):
             elapsed = time.time() - start_time
             time_remaining = report_waiting_timeout_delay_sec - elapsed
 
-        asserts.assert_greater(th_sed_later_bdbi_endpoint, 0, "Failed to find any BDBI instances with UniqueID present.")
-        logging.info("Found another BDBI with UniqueID (%d) on endpoint %d." % th_sed_later_unique_id, th_sed_later_bdbi_endpoint)
+        asserts.assert_not_equal(step_3_dut_parts_list, None, "Timed out getting updated PartsList with new endpoint")
+        set_of_step_1_parts_list_endpoint = set(step_1_dut_parts_list)
+        set_of_step_3_parts_list_endpoint = set(step_3_dut_parts_list)
+        unique_endpoints_set = set_of_step_3_parts_list_endpoint - set_of_step_1_parts_list_endpoint
+        asserts.assert_equal(len(unique_endpoints_set), 1, "Expected only one new endpoint")
+        newly_added_endpoint = list(unique_endpoints_set)[0]
 
-        self.step(6)
+        self.step(4)
 
-        self.th_sed_later_discriminator = 3333
-        # min commissioning timeout is 3*60 seconds, so use that even though the command said 30.
+        discriminator = 3840
+        passcode = 20202021
+        salt = secrets.token_bytes(16)
+        iterations = 2000
+        verifier = _generate_verifier(passcode, salt, iterations)
+
+        # min commissioning timeout is 3*60 seconds
         cmd = Clusters.AdministratorCommissioning.Commands.OpenCommissioningWindow(commissioningTimeout=3*60,
-                                                                                   PAKEPasscodeVerifier=b"+w1qZQR05Zn0bc2LDyNaDAhsrhDS5iRHPTN10+EmNx8E2OpIPC4SjWRDQVOgqcbnXdYMlpiZ168xLBqn1fx9659gGK/7f9Yc6GxpoJH8kwAUYAYyLGsYeEBt1kL6kpXjgA==",
-                                                                                   discriminator=self.th_sed_later_discriminator,
-                                                                                   iterations=10000, salt=base64.b64encode(bytes('SaltyMcSalterson', 'utf-8')))
-        await self.send_single_cmd(cmd, endpoint=th_sed_later_bdbi_endpoint, timedRequestTimeoutMs=5000)
+                                                                                   PAKEPasscodeVerifier=verifier,
+                                                                                   discriminator=discriminator,
+                                                                                   iterations=iterations,
+                                                                                   salt=salt)
+        await self.send_single_cmd(cmd, dev_ctrl=self.default_controller, node_id=self.dut_node_id, endpoint=newly_added_endpoint, timedRequestTimeoutMs=5000)
 
-        logging.info("Commissioning Window open for TH_SED_L.")
+        self.step(5)
+        self.th_server_local_nodeid = 1111
+        await self.default_controller.CommissionOnNetwork(nodeId=self.th_server_local_nodeid, setupPinCode=passcode, filterType=ChipDeviceCtrl.DiscoveryFilterType.LONG_DISCRIMINATOR, filter=discriminator)
 
-        self.step(7)
+        self.step(6)
+        th_server_directly_read_result = await self.default_controller.ReadAttribute(self.th_server_local_nodeid, [(root_endpoint, Clusters.BasicInformation)])
+        th_server_basic_info = th_server_directly_read_result[root_endpoint][Clusters.BasicInformation]
 
-        self.th_sed_later_nodeid = 2222
-        await self.TH_server_controller.CommissionOnNetwork(nodeId=self.th_sed_later_nodeid, setupPinCode=self.sync_passcode, filterType=ChipDeviceCtrl.DiscoveryFilterType.LONG_DISCRIMINATOR, filter=self.th_sed_later_discriminator)
-        logging.info("Commissioning TH_SED_L complete")
+        self.step(7)
+        dut_read = await self.default_controller.ReadAttribute(self.dut_node_id, [(newly_added_endpoint, Clusters.BridgedDeviceBasicInformation)])
+        bridged_info_for_th_server = dut_read[newly_added_endpoint][Clusters.BridgedDeviceBasicInformation]
+        basic_info_attr = Clusters.BasicInformation.Attributes
+        bridged_device_info_attr = Clusters.BridgedDeviceBasicInformation.Attributes
+        Clusters.BasicInformation.Attributes
+        asserts.assert_equal(th_server_basic_info[basic_info_attr.VendorName],
+                             bridged_info_for_th_server[bridged_device_info_attr.VendorName], "VendorName incorrectly reported by DUT")
+        asserts.assert_equal(th_server_basic_info[basic_info_attr.VendorID],
+                             bridged_info_for_th_server[bridged_device_info_attr.VendorID], "VendorID incorrectly reported by DUT")
+        asserts.assert_equal(th_server_basic_info[basic_info_attr.ProductName],
+                             bridged_info_for_th_server[bridged_device_info_attr.ProductName], "ProductName incorrectly reported by DUT")
+        asserts.assert_equal(th_server_basic_info[basic_info_attr.ProductID],
+                             bridged_info_for_th_server[bridged_device_info_attr.ProductID], "ProductID incorrectly reported by DUT")
+        asserts.assert_equal(th_server_basic_info[basic_info_attr.NodeLabel],
+                             bridged_info_for_th_server[bridged_device_info_attr.NodeLabel], "NodeLabel incorrectly reported by DUT")
+        asserts.assert_equal(th_server_basic_info[basic_info_attr.HardwareVersion],
+                             bridged_info_for_th_server[bridged_device_info_attr.HardwareVersion], "HardwareVersion incorrectly reported by DUT")
+        asserts.assert_equal(th_server_basic_info[basic_info_attr.HardwareVersionString],
+                             bridged_info_for_th_server[bridged_device_info_attr.HardwareVersionString], "HardwareVersionString incorrectly reported by DUT")
+        asserts.assert_equal(th_server_basic_info[basic_info_attr.SoftwareVersion],
+                             bridged_info_for_th_server[bridged_device_info_attr.SoftwareVersion], "SoftwareVersion incorrectly reported by DUT")
+        asserts.assert_equal(th_server_basic_info[basic_info_attr.SoftwareVersionString],
+                             bridged_info_for_th_server[bridged_device_info_attr.SoftwareVersionString], "SoftwareVersionString incorrectly reported by DUT")
+        asserts.assert_equal(th_server_basic_info[basic_info_attr.UniqueID],
+                             bridged_info_for_th_server[bridged_device_info_attr.UniqueID], "UniqueID incorrectly reported by DUT")
 
 
 if __name__ == "__main__":