A Guide to Multibooting a Mac
Disclaimer: This has the potential to destroy all the data on your drive. Make sure you have adequate (and verified working) backups before you proceed. You have been warned!
That being said this should leave all of your data untouched.
I have a mid-2012 15” non-Retina Mac book pro with a 1TB hard drive. I decided that I wanted to make my system faster by replacing the hard drive with an ssd and while I was at it I decided I also wanted to have Windows and Ubuntu partitions. Doing it this way meant that I had no data on the SSD while I experimented with partitions and boot managers although everything I did should be possible on a drive with an existing system.
- Multiple OSs installed with the ability to add more