Ar Extension For Belongs_To

I use CSaveRelationsBehavior in my project. It supports ~_MANY relationships, but ignores BELONGS_TO.

There is Order class which BELONGS_TO Customer. In Order form I can fill Customer data, can create the new one or modify existing one. I need an extension which saves Customer when saving Order. It should insert the new Customer record or update existing if PK of Customer given. There are many AR extension but I found veryfing them time-consuming. Maybe someone had similiar problem and found matching extension?

I can put some of my code if my issue isn’t clear.