Yep. We can never be mom, because BM is their mom. We can only be stepmom...which can still be very special, but don't go thinking it's the same thing. I'm 7 years in & still trying to learn what the heck this weird role I'm in is. I never wanted to be maternal with them, and BM is not very maternal either. She's so busy with work, school & her child with severe developmental delays that I can't tell how much she cares. But even if I never wanted to be SK's mom, it can still warm my heart when they call me that. I take it as them meaning that they feel affection for me & can rely on me as a figure in their lives. I do care about them. It's a bit awkward because I'm their sister's mom, and the degree to which I want to invest in each is like night & day. Anyway, a few weeks back SD came to me for puberty questions. I was happy to be able to educate (I didn't have someone I could ask questions) & relieve her anxiety & confusion. They are in my household cared for by me 50% of the time, so even if I'm not their BM my role is still mom-ish. I told SO about it when he came home, he told BM & they decided she would handle the initial puberty talk because it's "special" between BM & BK. Part of me gets it. The other part of me felt gutted. You'll dump your kid off at my house for half their lives, and benefit from my sacrifice, but I don't get to give them basic education on biology when they have questions? Oh right, because I'm not mom. Well then why the hell is your kid in my house every other week calling me mom?? The inconsistent expectations are very annoying. If SD has questions, I will answer them in an age appropriate manner. If BM wants to answer her daughter's questions that's fine, but if she doesn't want me to do it then she needs be taking care of her own children every day. You might not want to hear this, but it's true. BM & SM are not the same, they are distinctly different. If you want to be a mom you need to have your own child, then you will see how different it is & you won't have to compete with another woman.