Contact with Half Siblings During Childhood

Honestly, Im a bit nervous about posting on this board because I have tried it before with some really negative results. I am hoping this time will be different. I am also posting my ғquestion under several topics to get the most feedback possible. I warn you, itԒs long! ;) First let me give you a very super condensed version of my situation. After going through a nasty divorce and an even nastier disasterous attempt at co-parenting, my husband allowed his two children to be adopted by his exs new husband. They were ages three and four at the time. The oldest remembers my husband and myself, and according to the ex, the younger child does not remember much at all. At the time of the parental rights termination, the agreement was that my husband would still be allowed to have contact with the kids. His ex went back on that and we had no contact for over 2 years. Over the last year and a half or so we they finally allowed LIMITED contact. One visit was made by my husband but things went downhill fast after that. They were overly strict in how they would allow visits to occur. Yes, I know that is their right, but it was not something we were able to deal with. WeҒve since had no contact besides sending birthday cards the kids for six months. During that time his ex contacted my husbands parents and invited them to have very liberal contact with the kids and they are doing so. Now to current issues. I am now 5 months pregnant. I believe it would be best for the children, my baby and my husbandҒs two, to know each other growing up. Although they certainly cant have a remotely traditional sibling relationship due to the situation, I think they would benefit from at least not being strangers. I hate the thought of the children meeting someday after they(husbandҒs two) are 18 and being total strangers. Especially since my husbands two children do have contact with their paternal birth family(the grandparents), I feel it is only natural to give them the opportunity to know their half brother or sister as well. I contacted hubbyҒs ex to tell her about the pregnancy and request that we open a new dialogue about resuming visitations next year when the baby is a bit older. She has not responded to me, but did fwd my email to my father in law with a note saying IӒm not dealing with this. So I really have no idea where she and her husband stand on things since they wonԒt reply to me. In case you are wondering why I contacted her instead of my husband, its because she and I have had a lot of email communication in the past and I feel comfortable talking to her. My husband is willing to talk to them about things as well, but heҒs a bit miffed, as I am, that she wont respond to me at all. So now we are at an impass because she will not respond to me which is what my husband is waiting on, and the grandparents who do have contact with them wonҒt get involved because they are afraid she will stop their contact with the kids if they make her mad. Shes done it before. My questions to you all is do you have any suggestions as to how we may approach her to get a more positive response? It is a complicated situation so feel free to ask about anything you need clarification on.