Good morning from Texas! My family set-up is: my father, my mother (his wife), his “main” girlfriend and 2 “secondary” girlfriends which get changed usually every 2-3 years. Yes, we all live together in the same house - though it’s a big house - so it doesn’t feel crowded. It’s not a religious thing at all, we’re atheists.
I prefer mono, but wouldn’t mind poly. To explain: I want to be exclusive (don’t want multiple partners), but wouldn’t mind my partner having other partners as long as they prioritize me. Like my mom’s relationship with my dad.