After almost 3 years together and never actually talking about my role as "step mom" but just assuming we were on the same page, I talked to SO about it yesterday. I told him that I don't want to cross boundaries and do more "mothering" than he wants me to do. I love his kids and I have a naturally very protective and caring personality; I run a daycare and it's just natural for me to be that woman who flocks towards caring for kids. He told me he expects me to respect his kids and treat them as if they were my own. He expects me to help with discipline and routines and to help him care for them when in his custody. That's what I always did anyway, but it was nice to hear that that's what he actually wants. I asked him what he thought BM#1 wanted my role as step mom to be and while I don't think he's actually ever talked to her about it, we've come to the conclusion that she probably would expect me to love and respect her child just as I would my own. I do not test boundaries with BM; I help SO correct issues with SD5 when she is in our home, but all other issues are between BM and SO. I know that BM#2 wants me to have nothing to do with her child so when SO gets to see SD3 again, that will be a different situation. I'm just glad SO and I are on the same page and I don't have to feel like I should disengage from SD6 or anything.