Changing the type of an entity preserving its ID

Question

I am using hibernate as a persistence layer. There are 2 entities that live in the same table extending one superclass with single table inheritance strategy.

Answer 1

How do you distinguish between the two entities in the table? I assume that there some field value (or values) that you can change to make B into a C?

You could have a method where you load the super-class A and change the distinguishing values and save. Then in your next Hibernate Session your B will be a C.