I have 2 grown kids, 21 yr old at home & 18 yr old moved out/ both in college. My boyfriend and I want to take the next step in our relationship. He has 100 % custody of a strong willed 12 yr old daughter and an 18yr old son in college. I need any and all advise on step parenting his kids and putting my kids at ease that they haven't been replaced by a new family. His ex wife is very unstable and intermittently involved. The kids have lots of issues with her. Daughter is desperate for female attention and resentful that it isn't from mom. HELP!!!!!