I didn't post a reply until now for the same reason.
I'm running DW from the Amazon/Strategy First/direct download option.
I haven't had any problems running several RA installs (one at a time, of course). I'm also running Win10, 64 bit, BTW.
I start out with a clean install of DW which winds up inside the Strat First folder.
From there, I added the Win8 Win10 conversion DLL file.
I don't run the game from this location aside from making sure it worked. This is my secure "root" install.
To install a new version of RA, I just copy the whole DW folder out of the Strat First main folder to my desktop, unzip the RA install "package" and place it inside the DW folder on the desktop. Then I run the RA install and wait for it to completely install.
Once the install is complete, I'll rename the DW folder to something like "DWRA1.XX" and drop it directly into my C drive. I have something like 6 different versions of RA, but I also run a 1 TB main drive and space isn't an issue.
The Strat First version of DW comes with an additional program called LaunchDW.exe and all I need to do is click that to link the new install to my start icon shortcut (just click the start/run button in LaunchDW). From then on, the newer version of RA will launch when I click the task bar shortcut. I can also launch an older version by running LaunchDW from an older install.
This way isn't the most efficient but it works great if you're lazy.
One other note, this is NOT the Steam install. The one downside is that I doubt you'll be able to play it online via Steam.
I'd also warn anyone who's playing around with their registry to do so with a great deal of caution.
Reg edits can effect your entire OS.