Okay, I understood. One stable way is saving family in game library and then (when happens comeback) manually set their relationships with townies.
Thanks to all.

Late reply, but I was thinking might it not work if you just set most SP pushes for those sims to false so they were more likely to stay home? I've done that with sims I wanted to be at home more for my active sims to romance and/or friend them w/o having to stalk them around town.

The documentation for SP also talks about making castes not being allowed for lots but I've never tried that one myself because I keep forgetting it exists when I'm actually in-game.

Oh, that's an interesting situation too. Most demonstratively brag to all the friends that you are going on an exciting journey. Before leaving, stock up on food, in the house turn off the light, close the curtains, turn off the phone. However, there is no departure out of town. You just quietly continue to live at home until the "exciting journey" is over. And in any case don't forget that you need as quietly as possible to walk around the house, turn on the water, slam the refrigerator door and, most importantly, don't have a party.