It's very hard with blended families. I am both a stepdaughter and a stepmother. I mostly left my stepsons up to my husband to supervise and discipline. When my youngest stepson and I were alone, I had good one-on-one time with him and took cues from him on how he wanted the relationship to develop, whether fun/pleasant or more difficult and I kept my communications with him open at that time so he knew exactly why I was saying/doing what I said/did. There was some jealousy for my husband's time, especially when we were all together and I taught myself to bow out as I had my husband to myself more than his sons did. All three of his sons (and his ex-wife, her mother and sister and boyfriend too) and I have good relationships now that they're grown.