My advice would vary a lot depending on the following: Are you and your boyfriend living together, long term? How long have you been together? Do they live with him full time or part with their mom? Is she even in the picture? What authority have you and your boyfriend agreed that you should have over his kids? (i.e., none, some with deference to his ultimate decision, just as much as his) Does he ever undermine whatever authority you do have over them?