w7pro upgrade install failed

Hello: macbook pro late 2014. Bootcamped w7pro/high sierra. All copies legit. Attempted to do an "upgrade install" (repair w7pro OS, keep the 3rd-party programs) of w7pro. I have the w7pro SP1 DVD and I can create a flash install from that if needed. Here's the process I did:

-put DVD into DVD (external) drive.

-selected "upgrade" when the install process (setup.exe on the DVD) began.

-I did not closely monitor the "upgrade", but after an hour or so, all seemed to be going smoothly.

-after another couple of hours, I checked, and msg was, "could not successfully install this version. Reverted to your original install." (my words, but I think that's close enough.)

How can I successfully complete the procedure?

-Boot from the DVD (per apple support call, I was told no (don't boot to DVD), to just click on "setup.exe" as above, while within the currently open win7pro? -- -Or, create & use a flash installer?

-Or, monitor the install closer?

-Does mac need to be in safe mode (w/networking)? Something else?

Please note that I did successfully complete the same procedure (upgrade install to keep the 3rd-party programs, just repair the w7pro OS) without problems (1 try) on a gamer-grade tower windows-only PC about a month ago.

Please advise if this would get best replies in another forum.

Thank you.