Accessing another NAT routers

[PaleoAgTech]

I have a question. How do I need to config my IP addresses to access NAT4 router from NAT1 router? Accessing NAT1 router from NAT4 is not a problem but another way around it does not work?
Example: NAT1(192.168.1.1)<--->NAT2(192.168.2.1)<--->NAT3(192.168.3.1)<--->NAT4(192.168.4.1);

Do I need to play around with subnet classes or is there some simpler way?