Questions:
1. How close together are these three properties/families?

2. Why can't each of the family units work on solving their own sustainabilty problems for their piece of property. ie: rainwater roof catchment system for the property that doesn't have access to water? Garden space that will maximize produce output on each property to try and feed that properties occupants?

3. Are other family members coming to each property owner's homes but won't be bringing food stuffs and other supplies with them?

4. Is one piece of property only grazing capable? Goats, cows, & chickens but not able to garden? Is only one piece or two properties only able to support gardening?

5. What are the common factors to promote yall coming together? One grows meat and swaps that for veggies with the other? To provide for a common defense against possible looters/raiders? Are you all next door neighbors or are these three properties too far from each other for mutual support with food, water, defense, etc.

I do not want answers to these questions but am merely trying to provide some food for thought from different angles. Where there are disagreements, put yourself in the other party's shoes and approach the problem from their POV. Also, perhaps consider that you maybe working up an alliance with the wrong people if no one is willing to compromise.

Just my thoughts off the top of my head.