I'm wondering now about the kind of agency they are working with. If the agency is also run by conservative Xtians, your in-laws' attitudes could be classed as features, not bugs. I would say be honest in the letter, like you say upthread, it's a child's life in the balance.

OT: Icon love, is it shareable? My wife won a extra Switch in a raffle, and wants to suck me into Untitled Goose Game.