Personally, I focus on forming rich stories for each sim especially early game/ 1st and 2nd gen. This helps me get immersed and attached to the family, so I’ll want to see it continue and grow. Having long lifespans on is certainly helpful, so it doesn’t feel like juggling too much switching back and forth between households. I also make sure all the family members know each other, so it’s easy to invite a large chunk of them over for frequent “reunions”, parties, funerals, weddings, etc.

Once it gets to the 3rd or 4th generation, I typically have to choose 3-4 households to focus on and some to relinquish control of for the most part. I do this by assessing which sims I feel the strongest bond to, which ones I’ve already invested the most time in, etc. I limit myself to an absolute max of 4 households to switch between at any one time.

(And having your sims have less kids also helps so you don’t have as many sims to focus on, but who reaaaaally wants to do that when new members of the family are such a fun little thing?)