I amhearing you loud and clear, chippingin (and thank you for your thoughts. I hadn't really thought about mystep children inheriting when dh dies, if he goes first, will look into that and see what our provision is)
I notice that the thread has also gone silent since I set out our situation.
ime, on the whole, peopleare very biased towards children from first/previous marriages or relationships. The attitude seems to be,as shown here, that any subsequent children (and their parents) are money grabbing, and out to get whateverthey can. The attitude is invariably "well, he/she shouldn't ahve gone on to have more children", forgetting that those children, for the most part are already here, are wanted and affordable. It isn't a case of taking anyhting away from anyone, it is about sharing thingsout, fairly as you pointed out, within a family, whatever size/shape/form that family takes.
I note that everyone assumes that the OP's ex's ds must be resentful of his sister, if she shares in the house. Maybe he would behorrified that she would be left out?
He knows the OP and her dd (his sister) and has lived with htem. He considers them family.