Alright, so everybody knows that the most dangerous thing for a legacy is playing too far ahead, not having the right pictures, being forced to write about sims that you aren't even playing with anymore, the whole shebang. Pacing between your game and your story is super hard sometimes because you don't always feel like playing sims and writing at the same time, or you have to play really slowly, you al know the struggle.
This is where you come in with...the backup family!
Clone your legacy family at whatever point your story is at, and just keep them for pictures. That way you can play your normal family, and then still have the backup so that you can stay at the same point in the story, and still be familiar with those sims. Of course this may lead to some awkward positions, like clones being invited to parties and having to crop them out of pictures, but trust me, it's worth it.
(I always give mine kinda funny wrong names, by story mode is called the Aristocraps)

let me know if this is helpful for anybody!!!

Yes! This tip works wonderful! I do it for all my stories! Thank you so much for sharing it with everyone. It really does work! I can pick up my stories at any time while also playing my Sims as much as I want.

I basically do this too.

I am always throwing my legacy and challenge sims into mess about files or playing with a duplicate of legacy / challenge files ....
this also helps to give you ideas for story lines that you might not have otherwise thought about, after watching how your sims behave around each other.