Good news, everyone! The rescued baby made it!
I went down and checked her nest today while she was off for breakfast and found 3 eggs in the process of hatching. The furthest along, however, had an exhausted duckling stuck in a dried membrane, as did the next to hatch. I took them to the house, helped them finish, and also took the third one that was making progress, which also had a fairly dry membrane that was sticking to the duckling. All three are fine now, hatched out, and drying in the incubator.
How do I tell my mama duck to increase her humidity?
She still has a few eggs to go... Guess I'll check her at dinner time.
Still no progress on the 4 eggs fostered over to crazy mama.