Thanks @Decadian
All went without incident and the kids are off on a camping weekend.
I have been so focussed on empowering others I havent known how to claim my basic rights. My son seems to give her his decision making and it worries me a bit, but he has to work that out. I did ask her to back off once. I just said her name quietly, when she jumped in checking my kitchen shelves to check as he was getting organised, and she complied. I think that is a first for me... being obeyed ... wow. That is not her fault, that is because I caved with my step daughter and had to accept problematic behaviours to keep a semblance of peace in the home when kids were little. I have to learn to claim control more.
It feels very different to actually have a place I can talk about day to day stuff. I have never had that before. At school I was isolated and it was always changing. My family was too needy of my role as a support person. No space ever for my needs to be discussed. I was too placid and accepting with girlfriends, and also didnt really meet people who I was truly compatible with.
Today I am going to an 80th birthday party for a lady in my writers group. I like her. We agree about a lot of social issues. She also was a step daughter, as a young girl, and we had few cups of coffee talking about that, which I really appreciated. We didnt jump to defensiveness about our roles, as we had already bonded on discussions about indigenous issues. She had been Queenslander and seen a lot and cared about them. Everyone's experience is unique.