And I am 100% against it. SIL is a lesbian and her and her partner want to have a baby. They have decided that the partner will be the one to get pregnant because 1. she is the one who will be the SAHM so this way she will be able to BF and 2 she doesn't have a male family member who could donate sperm to impregnate SIL. They want the one who is not carrying the baby to get sperm from a family member so the baby will be related to both sides of the family. Here is the problem, DH is the only man who would be able to do this. His brother had a vasectomy years ago, their father is dead (and that would be weird anyway) and there are no male cousins.
DH said he felt weird about it but asked me how I felt. I think it is so wrong. We are married so him getting another woman pregnant (even through artificial insemination) just feels wrong to me. I asked him how he would feel if I donated eggs to his brother and SIL and they had a baby using that, he said he would feel weird about it. The other thing is, they said they wanted the child to know DH was the biological father once he or she was old enough to understand, so even to the child, he would be more then an uncle.
After discussing it, he told them that we just don't feel ok about it. They are angry with us because they feel like we are forcing them to give up what they want ( a child they are both related to). I don't feel bad, I am sorry they aren't getting what they want but it's not DH's just to provide SIL with the ingredient she can't contribute herself.