Open it in Excel or Google Sheets, change the yellow cells, and watch each family's share add up on its own.

Start with the housing cost. Set the percentage each family carries, because fair doesn't always mean even.

Then fill in the move-in money, the utilities, and even the shared car. Our own numbers are already in there as an example, so you can see how it works.

Bring it to your first family meeting, write down what you first agree on, and let everyone look it over and come back for a final review if needed.