As we had hoped, the clutch of chicks hatched out under the house stairs is still safe and healthy. The mother is very fierce and watchful. She's taking the chicks out foraging around the yard (and in my garden a couple of times, unfortunately), teaching them everything they need to know. The chicks are starting to get their true feathers in already.
Charlie follows them everywhere, and the hen seems quite comfortable with this. It's a perfect situation.