How to decople parent checkboxes Except children checkboxes

[yukwar]

Lets say I have this tree:

1. Parent 1
   1.1) Children 1
   1.2) Children 2
   1.2.1) Children 1
   1.2.1.1) Children 1
   1.2.1.2) Children 2
   1.2.2) Children 2

The option decoupleChildFromParent = true will set all checkboxes as independents, I need another option that the child that has childrens only decoples from its parent but keeps coupled with his childrens when the user checks it.

1. Parent 1
   1.1) Children 1
   1.2) Children 2
   1.2.1) Children 1 X <----- The user checks this one
   1.2.1.1) Children 1 X
   1.2.1.2) Children 2 X
   1.2.2) Children 2

Right now the parents of 1.2.1 are getting checked visualy

What i need is:
The childs of 1.2.1 will be checked and the parents will not have the state as intermediate or checked.

Do we have a workaround for this scenario?