DivinylsFan I meant a pointer in the computer sense, as a technical term.
The in-game move to new town feature was introduced with the Island Paradise patch, and a lot of features from that time never got fixed.
I don't know who told you not to go through the library, but they're misinformed.
If you want to see what would and would not be preserved when saving a household to the library, try it yourself. I'm only about 95% sure what does and doesn't get saved.
There's no limit to the number of times you can save your sims to the library and place them in a new save. There isn't a theoretical limit for the in-game way either, but in practice, things would likely break down before too long for the reasons I listed previously.
If you want to preserve memories and relationships and everything else from the old town, use NRaas Traveler's Change Hometown feature instead. It's described here:
https://www.nraas.net/community/Traveler-FAQ#Is-it-possible-to-switch-homeworlds-permanently