This definitely has a ton of taboo appeal, but I'm not sure how this will go for relationships where chars aren't related. Are those banned as well, as relations of amusement?
It's definitely been a question that has been raised before.
Each character, who is a member of the Church, does not
need to have another character for relationships and such. If you do a male member of the church, you don't have to have a sister to play against. There are a number of sheets already who are very much like that. I can think of a few off the top of my head. A single member of the church who is not married, or not attached to anyone at the moment.
I have a character in mind that I want to do, a female member of the church who has no husband, no father, and no marriage prospect.
The relationship section of the sheet is 100 percent optional. It's placed there as a way for there to be links to other character sheets, like my Prophet and his sister.
If you feel the need to have a character who is attached to someone, NPCs are always welcome. I don't do separate sheets for general NPCs just because it means more work for me, more claims that are taken up, and offer more troubles as far as organizing and such.