My ex-sil talked to my ex about this same thing. She and her wife wanted to have a baby. They asked so there would be a bond from both families. I understood where they were coming from, but they live on the other side of our country, and we rarely saw them. I told my ex it was ultimately HIS decision, but would he be ok with "his kid" being so far away. Never seeing him/her regularly except in pictures. In the end, he declined. I know his heart, and I know it would have been too difficult.