Ok, I've done all the steps as recommended, but when I first had them both in, I could only boot into 7, if I disconnected the 2tb, I could then boot into 10. The error it gave me when I couldn't boot was 0xc0000225 saying that I was missing a required file/it can't locate it, I think it was winload.efi. So I did some googling and did some repairBCD commands, however when I went to recreate the BCD file, with both the drives connected, it said the requested system device cannot be found, even though it knows there's another Windows install?
For now I am using Windows 10 and sorting out all of my settings etc, I don't really need the 7 install, it was just in case I forgot something in the next few weeks, if not I'll just nuke it. However whenever I restart it gives me the option to skip disk checking, which I've done every time so far, I didn't request it, could it just be part of the bcd commands that I executed?
Thanks heaps for all the advice!
edit: A picture of my disk management now, if it helps in any way: https://i.imgur.com/ZiByyE1.png
Also my msconfig boot options now only show Windows 10 as current/default.
2nd edit: Forgot to mention that when I first installed 10, plugged in my backup drive, accessed it with Reflect, I couldn't access videos/images save location, unless I disabled UAC: Run all admins in Admin Approval Mode. With that disabled I could then access my external drives files. It worried me though, this seems like too much of a simple fix to not bring it up.
Edited by Chryspa, 03 October 2017 - 01:38 AM.