We live in our garage apt (420 sqft). I posted about it here. let me see if I can find a link. It hasn't all been fun and games, but it's been a year and a half and we haven't killed each other yet.

[found a link[(https://www.houzz.com/discussions/post-harvey-tiny-living-dsvw-vd~5288240)

Yikes! I'm an only child so I've always needed "space" - just not used to a lot of "sharing" where space is concerned, and that would drive me crazy. I suppose it might work if one lived in a nice climate where everyone (especially children) could be outside much of the day. But winter in such close quarters? Well, better you than me! Of course, I live alone (with two small dogs) in a house with 2800 sq ft and don't find it big at all. Ha!

My parents did this, though not well, with their retirement house.

Give proper thought to the kitchen. I would even post a potential layout for your temporary kitchen to the Kitchen forum to make sure you get the biggest bang, and most efficient layout, possible. Posters there might also have some ideas that you haven't considered.

What climate/state are you in?

how to set us up comfortably for the next 6-8 months while we build

Declutter, so that you have only the bare minimum of stuff to store. I know this probably sounds crazy with four kids : ) .

Just in case, make plans to ensure that the entire family can be (reasonably) comfortable for at least one year, rather than just 6-8 months. Expect to spend December (and thus Christmas or Hanukkah or Kwanzaa etc.) in the garage. If you don't, it will be a lovely surprise. If you do, you'll be prepared : ) .

I would mentally sort through each month and season for at least a year, writing down EVERYTHING that everyone in the family (together and separately) does and needs for that month/season. Work, school, holidays, housework, friends/family commitments, etc.

I am at a loss on how to set us up comfortably for the next 6-8 months while we build.

Build a house in 6-8 months, and ready to move in - that sounds way over optimistic.