For the record, the culty terminology of calling each other brother and sister is not tied to the polygamy. It just comes with being a member of the cult in general.

It wouldn’t be out of place to stop a bratty twelve year old running around on Sunday and say to him “Brother Harris, I’ve already told you once to stop running in the hallways.” (Harris being the last name of the child.)

I’m not saying it isn’t 100% cult behavior, but it isn’t part of the multiple wives aspect. It’s just how they all talk to each other regardless of who is married to whom.

Like when you’re at the bank and a bank robber shoots a bunch of people and then you jump out from cover and start covering all the corpses eyes super fast.