In situations like this, it is best to use runtime folders from other versions as external runtimes.  Otherwise, you will need to reinstall all your content into your current program.  Keep in mind, extremely large content folders will slow down your app considerably.  Creating smaller external runtimes will ease the burden.

BTW, there is no beast called Poser 7 Pro; it is either Poser 7 or PoserPro.  Although they are similar in appearance, there are some added features in PoserPro not found in Poser 7.