HELP FROM STEP MUMS.....?

I get the subtle impression that my husbands Step Daughters would prefer he is not with me....being girls they come across as bitchy and make me feel uncomfortable, they never saying anything directly to me, it is just the way I feel excluded around them....the older daughters have a child each of their own and they make a big deal of calling my husband grandad and I get called nothing, this makes me feel crappy..I've have told my husband this and he says he says something to his daughters, by I doubt he does, and at the end of the day he cant force them to do anything, they are adults (immature ones). He has another daughter from another relationship, just to make the situation more difficult, my husband detests her mother (his ex), she causes alot of problems, now and in the past when they were together, she manipulates the daughter and makes me out to be the bad guy. Now I have just found out that the mother has forbidden the daughter to see me !! What a *****.... This is impacting on my relationship with my husband, are relationship is already under extreme pressure, on the verge of splitting up and now this. I have spoken to my husband about this and told him how uncomfortable I feel, he said it is not the daughter's fault, it is her mother. I feel like an outsider when I'm around them...Ive told him I dont want to attend functions or whatever involving his kids because of how I feel. Please help....