After talking with TwistedMexi about debunking a forcetwins cheat, he actually discovered cheats that can force multiple births. I've updated the
pregnancy guide with cheats that will force as many babies as your house can hold (max 8 members), but they are finicky and must be entered exactly right. Some people are saying they don't work, though I just managed to do it 3x in a row and capture screencaps for proof. You can have up to 7 babies, if in a household with a lone Sim who is pregnant by someone out of the household. Sims must be pregnant already for it to work, and the cheats won't produce the babies instantly. There is a separate cheat for forcing labor. Here are the commands. Head to the guide for further explanation.
Sims.get_sim_id_by_name firstname lastname (this gets the Sim's unique ID number)
pregnancy.force_offspring_count ID # - so type out the ID exactly as you see it, and end it with the number of births you want.
pregnancy.force_offspring_count 1341302010235 5 would spawn 5 babies in the stomach of the Sim with that ID (That's a crazy concept, but yeah..)
Then, the pregnancy will run its course. I've determined reloading breaks it, but am not sure about travel, CAS, etc. I think it's best done in combination with:
sims.add_buff buff_pregnancy_inlabor to go into labor instantly.
Thought I'd make sure you guys are aware on this side of the site, as I know some of our storytellers would enjoy raising 7 babies haha.
I'd love to hear some feedback from some of you on how this worked for you, assuming no typos in the ID. If people do testing and determine just what breaks it, I'll update the page with the proper info.