One teenager put it to me this way. I like my stepmom. That's the problem. I'm worried my mom will get her feelings hurt. What a bind for a kid. A child in that situation needs permission from their biological mom. Permission to get along with and maybe even love their stepmom. What the child needs from the stepmom is your permission to love their mom and a whole lot of grace when they shrink back. After all, it's not really a rejection of you it's just being stuck in the middle.