Validation on Save

   I have two entities in my database that are responsible to control the application access. The structure of "levels" is hierarchical and a specific level never has more rights than your parent.

AccessLevel 
----------------
AccessLevelID
Name
AccessLevelParentID 

AccessLevelRight
----------------
AccessLevelID
ActionID

When I remove a right from a parent, I need to remove this right (if exist) for all children of this level.

So, I need to create a kind of validation to assert this business logic. 

I thought to do this creating a validation in an entity partial class:
public override void Validate(IdeaBlade.Validation.VerifierResultCollection validationErrors)

But, in this validation, I need to execute a query and manipulate some data. I don't have an entity manager in that scope.
I can solve my problem creating a trigger in the database, but I don't want to do this.

How can I do it?