I also got MMM 16 Premium and installed some vst plug ins from older version of Music Maker and some from third party. It is not necessary that each third party (non magix) vst plugin in will work in Music Maker. You got to try and see. There isn't any surety if third party plug in will work or not.

To install vst plug in just copy the file in to the Music Maker16 Premium/Synth folder and restart Music Maker.

Hope above information will be helpful.

nihon94