The double-double
This photo is old, but shows the idea of my double-double. Not too nimble, so bike paths are a plus.
Since this was taken, my eldest daughter(6) is off the tandem and rides the front of the trail-a-tandem, where she can pedal and shift. (Photo had that spot not pedal-capable, just footrests). Middle daughter now (4) kid-stokes, and son (2) is still at the back in a seat.