I'm not a fan of mothers day at all. I don't expect my kids to tell me how terrific i am and how much they love me, that seems to be obvious all the time.  It's my job to love them no matter what, to  help them become healthy loving people and that in the end, seeing how they thrive, is my reward.  As for step-parenting, i think it's the same.  We're there to help the child, it is a one-way street, a necessary one.  It would be very hard to ask the step-child for a reward for that, especially when they're young.  How could it not feel like betryal to their mom.  I would hope the mothers would let their children know it's okay for them to love their step-mother,(never hurts to have more love in your life) I tried to do that with my kids and I think it eased their guilt.  But i have never understood this need for adulation - we are the adults and should behave as adults.  Perhaps on mothers day, step moms can tell the step-child how much they love them, that might be a good start.