First off thank you for your concern for the chick, I am aware of the dangers of a duck raising a chick, and I've made sure the chick isnt' anywhere it could get to water. The duck hatched the chick because she started laying where Duchess, Nugget's GF had been laying, I thought I got all their eggs out but some must have been under the straw and I missed them. The nest the chicken is sitting on is a mix if different hen's eggs and Big Sis just decided she was going to sit on them, some are hers.
My drakes are a full Mallard a full Runner and two Mallard/Pekin crosses and Mallard/Runner cross. The hens are all either Runners, or a combination of Mallard/Runner and one Mallard/Pekin. I have two other hens who want to go broody and have started "hiding" their eggs from me.
The baby is doing well this morning, safely tucked under momma's wing when I get anywhere near them. I'm just glad she didn't abandon her nest when the early one hatched, I was worried about that. I'm also wondering if Big Sis realizes that the baby is a chicken and should be on her side of the big nest!