Here we go again - yet another thread where Lars computer upgrade issues and doesn't pay attention to what he's been told. First off is compatibility between operating systems and PT. For the umpteenth time here's the link to the compatibility page:
http://avid.force.com/pkb/articles/e...tibility-Chart
And yet again incomplete info on your computer system. Why not just put it all on your profile page? You leave out things like what exact model you have. Or system drive type and size. Those are important. Basically there are three mid 2012 MBP's and they all can take a max of 16 gig ram.
Darryl has given you the basic steps to make extra partitions on your system and that is accomplished through OSX disk utility. You could probably get away with a partition size of 128 gig but you'd be better off with at least 256 gig. On my old iMac I had three boot partitions: OSX 10.8.5 at 512 gig, OSX 10.9.5 at 512 gig and OSX 10.10.5 at 1 TB (it was a 2 TB drive). Of course if your system drive is one of the 5400 rpm spinners you're just spitting into the wind and will have to swap that out for something better like an ssd. You'll not only get better performance with the ssd but your battery life will be better and the computer won't get as hot as with a spinner.
You've been given advice here by some of the best at what they do and you continually ignore it and make trouble for yourself.