Entity Framework 4 TPH inheritance, how to change one type into another?

Question

I have found some information regarding this but not enough for me to understand what the best practice for is for this scenario. I have your typicaly TPH setup with an abs

Answer 1

Yes, you got it all right. EF inheritance does not support this scenario. The best way to change a Firm type for an existing Firm is to use a stored procedure.

Please take a look at this post for more info:
Changing Inherited Types in Entity Framework