My SO has a daughter who's biologically his.  He also has a son, who isn't actually his.  He was 6 mos old when he got together with his mother and raised him as his own.  When they split they agreed not to tell him the truth but being the spiteful bitch that she is she told the child that his father was not really his father.  This child has done nothing but try to drive a wedge between him & I & try to get his sister on board with it as well.  It bothers me when my SO does what this child wants over what I want.  For example: made my SO come over to his mothers house to "talk" about the fact that he feels when they're at our house I should not be aloud to ask them to do anything, like pick up after themselves. My SO actually agreed to this even though in my opinion it's my house I pay most of the bills he barely helps with anything because he had a terrible paying job and has to pay child support. He contributed what he can but it isn't much.  I feel I have a right to say whatever needs to be said especially if he's not.  This is my house and I don't feel I should be over run by a nine year old that isn't even biologically his & I feel should not be my problem.    Sometimes SO is always doing everything for this kids and chooses him over me. Other times he says "not my kid, not my problem" (only when talking to me).  But if he feels that way than why should I have to put up with being over run and this child causing problems and not following the rules. He should just leave him with his mother and be done with it. Can't say both ways. Can't do everything for the kids and blow me off for that kids that isn't his and then say "not my kid, not my problem".   Just not sure how to approach this subject. He either wants the kids or not.... I personally feel that the child should just stay with his mother.