My ex husband and his new partner had a baby in December, they have not told my DD ( his child) about her half sister. I found out via child maintenance telling me my payments have gone down. I've told her today as she has a right to know about the said new baby. She doesn't seem bothered and the only question that she has asked is is he still my father or just the new babies. Aibu to have expected him to tell my daughter that the baby had been born and a little information about her, eg name. He was court ordered to write to her and he hasn't even done that.