Lurking from the ttc>35 board, hope you don't mind my input!
My uncle's son converted from Catholic to Baptist, my Uncle has baptized all his grandchildren, I don't even know if any of them know it, but my mother told me. the children are all very much into their baptist religion. there are emergency "baptisms" which might be the way the family could decide to go....its a tough call and I wish you the best in navigating the tricky road.
But I appreciate all your posts because I have been struggling with this idea, if we ever get KU. I am raised catholic, I participate on my terms, my husband is jewish, he participates in on his terms too, we would raise our child to honor both religions, I think we decided if its a boy to raise jewish, a girl catholic. But that deep religious upbringing occasionally panicks at my non existant child possibly not being baptized.