My boyfriend has a 4 year old son that he has full custody of, and 18 and 14 year old children from a previous relationship. The mother of the 18 and 14 year olds told their case worker that the 4 year old is not biologically his. His name is on the birth certificate, and the mother gave him custody. With his name on the birth certificate, doesn't that give him legal rights to child support even if he's not the bio father (but we strongly feel that he is)?