Public geometry issue with Creo8

Hello,
We have been using public geometry in an assembly (creo5) for several years and in this public geometry there is a compound surface (bottle), which we use to hollow out another part (mould). The usefulness of the public geometry is that we change the bottle for another one and the mould automatically updates itself (height, diameter, etc.) to match the new bottle.
However, since we have been testing Creo 8, we cannot change our bottle without causing an error: it does not replace the old compound surface with the new one.
I can't attach the video to show you our problem.
Maybe we did it wrong a long time ago, but that's how our files are. If we got it wrong, what should we do?
I am still available to answer your questions or to send you our files.
Thank you in advance for your interest in my question.