Hazel- I'm not sure it will necessarily be confusing to him. My foster son refers to me as mom, but he has several "Mommy ____" as he refers to his birth mother, and a few previous foster moms. I don't think kids at that age really realize what "daddy" means..it is no different from having several aunts and uncles. They all have the same prefix, too.

By the time he is old enough to really know what "daddy" means, he will be old enough to know who his real dad is.

Sorry that it is frustrating to you, though..but I think he is lucky to have so many "parents" to love him :-)