I have a laptop an desktop that both have Win10 on them and I was going to add Ubuntu 14.04 LTS 64 bit on a side by side install. I've seen lots of issues with machines that already had Ubuntu installed alongside Win 7 or 8, that showed up when attempting to upgrade to Win10.
I have not seen anything about problems of adding Ubuntu with Grub to an existing Win10 machine. Any dangers in doing this?