I don’t know how to do dual/multi-boot computers. Wish I did, but I run Linux Mint v18.3 occasionally from a thumb drive.
It can be a challenge, no doubt about it. Waaaaay back in the mid 2000’s I multi-booted a PC with Windows 95, 98SE, 2000, Vista and Linux. THAT was a real trick! I think I impressed the instructor with that one, and all the O/S’s worked!