Dear InaccessibleB,
I know it's been a while since anybody commented on your thread.
Just wanted to post a little note to congratulate you on being so open and vulnerable, especially within this space. Your responses were very respectful.
Your need for acceptance may never actually be met by the bio mum. And yes, you are most welcome to use that term, it is not derogatory at all; it is a legitimate scientific term describing their relationship to their child. Unfortunately, whatever name you use, and however you exist in this situation with your step-children, you will never receive acceptance or reassurance from bio mum. Nor any bio-mum, clearly. You will have to find it in the way your step-kids interact with you. They are your gauge, not their mother or any other bio-mother.
No mother ever feels 100% okay with their child being exposed to another potential mother figure, regardless of whether you are nice, mean, older, younger, more attractive, have kids... you are never going to gain her acceptance. You are a reminder that her relationship failed, and that she is not the only woman providing care in her child's life. The minute you get between a mother and her child, there will usually be some unease. Especially if you do a good job, god forbid a better job than her.
So please, keep sharing special time with your stepchildren. Love them as much as you can, be there when she isn't. Be the spare caregiver that keeps them safe and loved. I've learnt first hand that you can literally save your little step-child's life and be there when neither parent can be found ..... and you will still be treated like scum a few days later. Love as hard as you can, you beautiful caring woman. It's people like you who love without expectation or conditions, that create better humans and a better world.
The more restrictions you face from bio mum, it usually indicates you are doing a good job and possibly making her feel insecure. I've been banned from one-on-one time, school involvement, family photographs, graduation ceremonies, Facebook mentions, even baking a cake for BM with my step-daughter was prohibited at one point.... as kids got older they started telling their mum they wanted me there. And that was the sweetest form of acceptance I could ever ask for.
Good luck with the bio-mum. I fondly hope she gets to enjoy being a step-mum one day and realise the silliness she caused :)
My best wishes to you.
x StepLightly