One of our Silkies, Arrowroot, went broody a few weeks ago. After I was sure that she was determined, I gave her two eggs from BC's flock (mostly hatchery NH and one BR) and one from Timmy's flock (BR/NH/EE mix). I left her in the nest; the other three Silkies are still sharing the coop and pen.
The eggs were due to hatch tomorrow. I had to be away today but I phoned DH before heading home to see if there was anything we needed from Tucson (about an hour away). He said that an empty eggshell was on the floor of the coop but that there wasn't anything inside. I asked if there were any chicks under Arrowroot but he hadn't looked. When I got home, I heard cheeping from across the yard. Inside the coop I found half an eggshell and a fluffy chick on the floor. The other three Silkies were in the opposite corner. I scooped up the chick, apparently a New Hampshire, and put it under Arrowroot who accepted the chick and pecked at me. I checked under her and saw a second fluffy chick, apparently mostly Barred Rock, and the third egg. DH and I added a short barricade across the front of the nest for tonight to keep the chicks in. (It was 26°F in the coop last night.) The set of three nest boxes are supported on concrete blocks. Tomorrow, when the other three Silkies are out in the pen, we will either move her, the chicks, and the nest to the floor or take out the two support blocks and lower all the nests to floor level.
I will check again before bedtime to make sure that all chicks are under Arrowroot.