Great, Drummer, for stepping in! Yes, Tjun, he's the guy that got my similar set-up working correctly so I defer to his expertise! Follow his directions and you'll be up in no time.
I did my Win10/Linux (which is Ubuntu) Mint on separate disks and it's working fine. There is an option in G2W to force it to take over from the Win Boot Loader, too. The directions and YouTube posts are pretty thorough but one thing I made an error on was not moving G2W to the top of the hierarchy in that step and Win kept taking over. Also, Win and Linux use different methods for identifying HD's so be sure to choose the right Linux boot drive for installation and you should have no problems. If...