When we want to delete a content in a hierarchical reference table, if the content or one of its children is referenced that is going to be deleted is referenced by one of those contents it should be deleted.

For example, we have this hierarchy :
A
 -  B
 -  C
 -  -   D
With this references : 
(A->B)
(B->D)

We should be able to delete from A or B but not from C or D because D is referenced by B wich is not in the C hierarchy.