I have been able to go back to Studio from Bryce a couple of times.  But I find it is really sensitive.  If you haven't broken the links to Studio then you should be able to go back into Studio and make the changes.

Hopefully someone else will chime in as I haven't tried a lot due to the fact I had Bryce crashing frequently for a bit.  Seems much more stable now after some other tweaks (change in video card, etc.).

 

Brett