Just to close out this story... I followed the instructions in howtogeek.com's article, and used EaseUS Partition Manager.
Long story short: I destroyed the boot mgr on my primary Win7 OS disk, and could not restore it (and I tried many different techniques...). So don't use that utility. Instead, follow the good advice given on this thread.
I ended up disconnecting the HDDs and inserting the Windows 10 install media I created earlier in my Windows 10 upgrade adventures... and doing a clean install onto the SSDs.
Labor Weekend was spent re-installing ALL THE THINGS, and copying files across from the two HDDs.