Birth mom behavior
Husband and I have been married 8 yrs., he has 3 adult children and I have 2. Have had difficulties with BM in the past with very controlling behavior on her part, but it had settled down some as my SC have gotten older, moved out of town, etc. My 29 yo SD has a very dependent personality and tends to do what her mom or her bf(boyfriend) tell her, and is very afraid of conflict. She informed us this past summer that her mom wants her to get engaged and wants her and her bf to buy a house. She told us her mom said that "me and your dad will give you the down payment for a house as an engagement present". At the time her dad and I expressed surprise that her mother would tell her we would be giving her money for a house when it hadn't even been discussed with us. My SD expressed mild surprise too, but does not confront her mother about anything. BM has a financial background and believes she knows best about finances as well as what is best for her children. BM is strongly pushing for SD to buy a house before the end of the year. SD's bf does not like BM but is in agreement about the financial importance of buying a house before the end of the year, and now he is also pushing SD to start looking for houses.
I'm finding the more this comes up, the more stressed I feel. I have talked to husband about it and aired my conflicted feelings. We have always wanted to be able to help our children financially. However, 1)we didn't think through that we might have kids buying houses while we still have two kids (my kids) in college (my ex not paying for anything for multiple reasons), and 2) I'm really peeved about BM "deciding" we will help with down payment. We don't know what we can do yet financially, and if we can help, we would like to get some pleasure out of it. I am concerned that if we give the down payment as BM has decided we should do, we will simply be letting her know that telling us what to do works. This is not new behavior and not simply directed at us. BM tells all her kids what to do, but is most successful with telling SD what to do. SD does not set limits with her mother at all and tries to view it as simply her parents not getting along. In addition, while my husband is verbally in agreement with my reluctance to give SD money under the circumstances, my experience in the past has been that he often (but not always) backs down in the end. I do realize it might be very uncomfortable for him to not help SD with money down when BM and most likely bf's parents are also helping. I also feel somewhat guilty in that when we married my ex was paying child support and helping with other financial stuff for my kids, but it has fallen on the two of us to pay for my kid's college and most of their other expenses the past few years.
I'm looking for ideas on whether I should see what happens, let this go, push to not give SD the money so ex gets the message this type of behavior won't work (keep in mind there will also be a wedding to deal with), or disengage and accept my husband has to deal with it how he wants?