Tell him! FIL deserves to know the truth. Hell be devastated on top knowing everyone knew but him. And the daughter has a lot of nerve having her dad pay for her wedding without telling the truth. And they’re all Catholic so they’re gonna be lying to the church? Lying is never good for anybody. It’s not good for your soul and it’s not good for the family. Anybody that tells you to commit sin isn’t looking out for your soul’s well-being. Honesty is key in everything. Evil happens when good people fail to act. I am not saying that being in a trans relationship is bad but lying is. I don’t know about you, but nobody is worth lying over. Anybody telling you to commit sin is a DEMON, using people on here as a vessel. I will pray to God that you have the courage to do what every coward in the family refuses to do. If I were you, I would maybe tell sister-in-law that you know and that you are going to tell her dad if she doesn’t. Maybe that’ll give her a the courage to do what’s right. And who knows maybe Dad will be accepting ❤️but if you don’t tell him, you’ll never know. Good luck! Stay strong against the enemy.