Can't put brother's wife in his party

[Carface Is My Spirit Animal]

I don't know what's going on, I have him in my army, he's leading his own party and I'm trying to stick his wife together with him to up the baby chances but it won't let me donate her as a troop to him, why does this company make such simple things such a hassle?

[Action Man]

I don't think you can in the vanilla game?

If you're trying to get your sister-in-law pregnant, as long as they're in the same settlement (so he's attached to your army), the game will still do the pregnancy check.

[Clovis Sangrail]

You cannot put a family member or companion in a party (or caravan) led by another companion or family member. Period.

This is a game, and games have rules, and this is one of those rules.

[TruXurT]

Well it is the way they set it up. If you are in a faction though, you can call up your brother's unit to your army and this way you can rest your army in town and he can meet his wife there.