Both families have been in isolation for last two weeks with grocery store and takeout/drive-in exceptions (hand-washing religiously following these exceptions). Kids have not been allowed any interaction with another child outside of their family. For the grocery store exceptions, the same adult from each family is going and building a sanitizing routine in the process. Both income earners in the home work fulltime remote.
We are now ready to begin interacting with this other family (letting our kids play at each other's homes, playing games/watching movies at home with each other, etc.). Once that starts, the agreement is that if anybody in either family has contact outside of our circle, both families (and children) go back into isolation again for two weeks. We've had a couple others in our neighborhood want to join, but they cannot commit to full isolation outside of the circle. We'll see how it goes...