In the Library Palette ...
  On the upper right hand side ... Look for the File Folder with the Plus (+) sign and click it.
Now ... browse to your Poser 7 folder and click on it to add it to Poser 8.
And, ... that's all there is to it.

cheers,
dr geep
;=]

P.S. If you deinstall Poser 7, you might lose the Poser 7 "Runtime"
If you do this ... you will lose it.

Here's what to do ...

Make a new Folder in your root directory (NOT in the Poser 7 folder)  named "P7Runtime" (or what ever you want).
Copy (or Move) the "Runtime" folder from your Poser7 directory to the new folder.
Now, you can deinstall Poser 7.
Now, "Add" (in Poser 8) the new folder you just created as a new Runtime in Poser 8.

Remember ... "With Poser, all things are possible, and poseable!"

cheers,

dr geep ... :o]

edited 10/5/2019