I put some under our broody little feral Black Tailed Japanese Bantam hen. I guess she's doing everything right. I had to clean one egg she busted up but that was really my fault. I opened her coop door too fast and she freaked. She's very flighty. I think I put a couple Cuckoo Marans and maybe and EE or 2. I was putting food just outside her coop est door but she wasn't eating it. Now in the evening I crack the door, she creaps out and I put some food near where she lays on the eggs. I see her eating it when she goes back in so that's good. I'm glad she's eating as I've heard they won't sometimes right? Now that's she's in solitary confinement, the nesting box is being used finally and the eggs are clean.
I hope they all hatch! The dark brown eggs are Golden Cuckoo Marans, slightly different than the Cuckoo Marans as the main coloring is golden rather than black. Keep us posted on the hatch.