Validation to check for a node in two separate hierarchies in same Viewpoint

Summary

Validation to check for a node in two separate hierarchies in same Viewpoint

Content

Please consider below scenario - 

One Viewpoint

Two hierarchies

Three node types

Data structure similar to below - 

Hierarchy 1 ->

A1(Node Type 1)

                       B1(Node Type 2) 

                                                C1(Node Type 3)

                       B2(Node Type 2)

                                                 C2(Node Type 3)

Hierarchy 2 ->

A2(Node Type 1)

                       B3(Node Type 2) 

                                                C3(Node Type 3)

                       B4(Node Type 2)

                                                 C4(Node Type 3)

A1,A2,B1,B2,B3,B4,C1,C2,C3,C4  are the values. Node type is mentioned in the bracket.

Can we build a custom validation, if we add any 'Node Type 3' to any one of the hierarchies above, if the same value of node is not present in the other hierarchy error should be thrown?