Hi Evan,
It is extremely dangerous to switch datasessions during a form's life. You may lose your connections to the tables altogether. This is definitely not recommended.
If you are gradually switching your architecture from using the default session to using a private datasession, you need to use some control mechanism other than switching data sessions. I can't offer specific advice since I don't know what your current architecture looks like, but if you create your data environment using code, the basic idea is this:

IF this form uses the old style default data session
start up using default data session
ELSE
start up using private datasession
ENDIF

This would probably have to occur in the LOAD method.


Regards, Chaim