R.D.
Is this really the way she wants to announce to people that she is having a baby? If not, he can let his friends know mom's name before the invite is sent out. If he's not close enough to them to have this conversation before the shower, should they be invited to the shower? Also, when the baby is born, most likely it will have mom's name while in the hospital until they file paternity affidavit that states he is the father. So they will want to know her name if they are to see the babe in the hospital.
I love the wording, and several ideas on how to add dad's name without ruining it. You have a great imagination!