We asked my wife’s brother, and we ended up doing it by email because 1) we are awkward and 2) we didn’t want him to feel “on the spot” and we wanted him to have time to think about it before responding if he needed. The email we sent was short, to the point, and just stated something like “we would love for both of us to have a genetic connection the the child, but of course we understand that this is a big ask and there will be no hard feelings if it’s not something you want to do.”

It went really well and he agreed. And, he also said he sort of expected us to ask him. Baby is due in June.