Just let the installer install P8 where it wants, that will be under SmithMicro/Poser8...so it will be right next to PoserPro (under the same SmithMicro folder, okay?)
Then open P8 and add a runtime (folder icon to the top right) and point towards PoserPro folder.

So now you can run Poser 8 and access all of your other content from PoserPro or whatever other Runtimes you've added. And you can also run PoserPro seperately as a stand alone without P8. I've been popping in and out of both programs during the whole beta testing process and haven't had any problems.

If you do have some issues they mostly come from not updating your video drivers, but I personally have not had any problems to date.

Hope this helps!

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