One of our hens raised a (unfortunately lone) duckling this year, a couple of others didn't hatch. She is an excellent mother and we didn't want chicks. There were no problems, from day one Mum would dust bathe while duckling swam in a water dish. They stayed in with all the other ducks and chickens as all our's do and there are never problems till the boys grow up, and even then it's not serious. She started to sit again before ducky wanted to let go, but it just used to sit next to her for a while at a time. Now she has five chicks and it still wants to be a chicken. But it is starting to hang out with the ducks a bit when the nowty lady will let it but retires to the hen house rather than duck house at night.