Custom validation for a level 0 member under same viewpoint but different hierarchy.

We are looking for a custom validation to validate the count of level 0 members under two hierarchies belonging to same viewpoint as below.

1. We have one viewpoint with two hierarchies viz. management and statutory.
2. For every addition/deletion/renaming/movement of member in management hierarchy or statutory hierarchy, We want the count of level 0 members in both hierarchies should be validated.
3. If count does not match, then system should populate a warning message during request submission and vice-versa.
4. Existing count of both hierarchies - management and statutory should remain unaffected

Regards

Prasad B.