Open adoption-visits how often for sibling?

Originally Posted By TeresaHello. My name is Teresa and I have a 15-month old son that we adopted at birth. We knew the birthmother prior to her pregnancy and opted to have an open adoption. She is divorced and has an 11-year-old daughter that is the half sister of our son. In the first year we saw one another about four times. Each time has been very difficult for the child. She is not going to counseling and has stated that she doesn't feel comfortable speaking to someone about it. I talked to the birthmother about this and she said that her daughter said she wanted to talk to me about her feelings, althought i haven't heard from her as yet (and I'm not sure I'm the best person for her to talk to anyway). We don't have a 'structured' agreement as to how often we see one another, but I am thinking that we need to do that. I feel that two times a year may be better because of the difficulty it causes. If I had to guess, I would also say that it would be easier for the birthmother. I think the last time we visited was done more for the daughter and wouldn't have taken place if it weren't for her daughter wanting to visit. It seems that maybe the frequent visits haven't allowed the child to 'let go'. I want whatever is most healthy for her, and at the same time I need to do what's best for our son. Please advise me on this subject. Thank you for your help!!