You have that backwards. Open seating (the way WN does it) involves boarding families with children between the A and B groups. They're not getting front row,

You have that backwards. Open seating (the way WN does it) involves boarding families with children between the A and B groups. They're not getting front row, but they mathematically can sit together no matter how many of them there are. That is, unless the family only has C boarding passes and waits for their C rows to be called. On a different airline, I've witnessed, firsthand, families all booked on noncontiguous middle seats in the back of the plane. Once one of them tried to sit in my aisle seat, and I got to choose between an uncompensated downgrade to their middle seat, or narc'ing them out to the flight attendant, for whom I have zero trust that they'll not make things worse for everybody. Having met multiple prison corrections officers and flight attendants in my lifetime, my order of trust to help me with my interpersonal issues goes Southwest, CO, non-Southwest.