Thanks for the information, @Critter-3 . It's very informative.
I'm using TurboTax Deluxe, the CD/download version. It looks like updates to handle the unemployment credit have been incorporated in the many updates that have come through since March.
On review of the return that we filed in March and the Form 1040X generated a couple days ago, the $10,200 credit was appropriately applied. I was able to easily e-file our - ours and our son's - returns. We both have refunds coming. I did notice that one cannot have a refund from an amended return direct-deposited into one's account. Oh well. We'll wait to receive the checks.
As for the state return: It shows that there's a $0 balance on both returns. Comparing the returns from March and those generated in the amended process, the AGIs changed. Since our state - Kentucky - does not give the $10,200 credit, we don't receive a state refund; however, we do not owe the state any more money. We will file the returns with the state so they have our current data on file.