I had my old computer's hard drive fail so bought a new one. But subsequently bought a new hard drive for the failed machine so now have two windows 10 machines on my desk next to me. I have different stuff on both. I have three external drives (500Mb, 2tb, 200gb). One machine is on the very latest win 10 and one on the previous version.

I have a cheap and cheerful network switch (buy one for about £10 that would work plus a couple of cables) and just have a little network of the two computers and share whatever resources I want between the two. In the process they both have internet access of course. The 2tb drive is attached to the new machine but shared so that the 'old' machine (with the new drive) can access anything on it when I bother to turn it on. I also use the 'old' machine to back up some of the stuff from the new machine.

On the new machine I also have a Windows 7 Virtual Machine set up which I use as a little safety area in case there are any files I have any concerns with. I may also set up a secondary virtual machine with XP on as I have one or two legacy programs that I might want access to (a VERY old Adobe Guitar Tracks for example)

I would have thought that creating a very simple network would be an easy way to go and get rid of many of your frustrations. I can shift anything round as I choose easily and it's easy to share any resources I need. The new machine doesn't have a CD/DVD drive so I just share the one off the other machine if I need it.

I also may go back to using Teamviewer again between the machines and ipad as well so that I can access any of the machines from anywhere I might be. One of the attractions of Teamviewer is that I could run both machines from the one easily.

The monitor I have will take HDMi and VGA input so I have both computers attached to the monitor and can change the input with two presses on the front and easily switch between machines so the Teamviewer thing is not worth doing apart from the ability to remotely access the machines from anywhere I have an internet connection.

I may have misunderstood your problem!