OK, new SSD drive came yesterday, Sunday. But was left on my porch while we were at church, and ate lunch out, and it got freezing cold. So, I brought it in, and didn't do anything until this morning.
Now that the other drives were completely decrypted, I was able to install the new drive in SSD slot 2 (replacing the D: user files drive) temporarily, and use Macrium to clone drive the 256gb C: to it. Only took about 4 minutes. I also remembered to expand the volume at the same time, lol
I then swapped the old 256GB C: drive for the new 1tb T500 drive, and reinstalled the old user file D: drive in slot 2, and put my laptop back together.
It all works perfectly now, and it's been about 1 hour so far and NO issues. Oh, I did get prompted by the Crucial Storage Executive software to update the T500's firmware. That also went without a hitch, and I've rebooted again after that.
So, I'm all ready now for Windows 11, when I'm finally forced to upgrade from Windows 10. The old drive just didn't have enough space, and I didn't want to take a chance.