The No Threat Message

The answer to this question is important because a child who thinks you're trying to take their parent's place will likely work hard to prevent you from doing so. So, just tell them and tell the biological parent, too. A stepmom might say to the Mom: "I want you to know, that I know, you're the mom, not me. My job is to bless your kids, not get in the way." Doing this lowers the child's and the parent's sense of threat and their need to oppose the stepparent. It invites cooperation.