Better news this morning: the two kittens are still alive. It's getting close to noon now, but when I checked them around 9:00, they were fine. I let mom cat out to get a bit of exercise, which I supervise, then she went back to the kittens. I am hoping these two survive, and both are male, so I may just keep them -- a black-and-white one, and a yellow striped tabby.
I have housework to do, then will go on my bike ride. Another gorgeous day in the South, with temps in the low 70s today, brilliant sunshine.
Here's hoping better luck with the two remaining kittens!