Or, if you are worried and want to keep the old MVP file intact for MEP, copy the MVP file from it's default location, probably some like:
C:\Users\Your_name\Documents\MAGIX\Movie Edit Pro 2016 Premium\Projects 2016
to the default location for VPX, which I suggest that you create as:
C:\Users\Your_name\Documents\MAGIX\Video Pro X\Projects
In VPX, hit Y for Program settings, Folders tab, and change the default for Projects to the above. I think that by default it is created by the program without the subfolder Projects, so do it or change it in the Program settings.
Also, you may want to create subfolders for projects by themes if you create many projects.
Note that the only potential problem is if you had audio recording that you created using MEP. These would still be under the MEP folders and not moved. In this case and to be on the safe side, keep everything under
C:\Users\Your_name\Documents\MAGIX\Movie Edit Pro 2016 Premium