I tried it both ways:

https://postimg.cc/Jt5KGSDp

https://postimg.cc/k6c8g318

btw I like your idea of moving all the data to a dedicated external hd
but I was thinking if I do that then I'll also have to create a backup
hd for that, correct?

I realized that I don't need to move anything once we clone the drives
with Win 7 Pro. I just need to delete everything off the 8500, one folder
at a time, correct?
I thought what I would do is take a screenshot of all the folders of My
Documents from the newly created hd that we'll use as a dedicated data
drive and use it to check the folders as I delete them off the 8500 one by
one
Not get ahead of the problem were having with the 780 but how do I
create a backup if my data is on an external drive? Can I do a backup
from an external drive to an external drive? If so, could you please give
me numbered step by step instructions like you did before when we get
to that point?

Since I'm already backing up the 8500 and the 780. I think I should
buy more hd's next month so I have spare hd backup's for all the computers.

Thoughts, suggestions?
Robert