Re: make poly relationships
Mods:
MC Command Center: The MC Woohoo module includes a "disable jealousy" option under MC Woohoo -> Woohoo Reactions
Wonderful Whims: You can give your Sims the "wonderful attribute" Polyamorous!
No mods (does involve cheats):
Base game: Control-shift-c to open the console, testing cheats on , and then Traits.equip_trait Player. If you want extra satisfaction points as well, instead turn on testing cheats and then set their aspiration to Serial Romantic and type Aspirations.Complete_Current_Milestone until the aspiration is achieved and the game gives you the Player reward trait. Do this for all the Sims you want to be in the relationship.
Get Together: Press the U key to open the club interface (if you have Discover University it might show you university organizations instead, but there's a tab to show you clubs). Create a new club ("Polyamory club"?) and add the Sims you want to be involved. Add the club activity "Be romantic with" and choose for the target of that activty your club ("Polyamory club"?). I like to add banned action, "be mean" as well because that's the way I roll.
Eco Lifestyle: Shift-click the mailbox and choose Instant Add NAP (cheat) and choose the Free Love NAP. Just be careful, if this is the only one you're using, to only be romantic at home because the no jealousy part only works in the neighborhood.