I'll see this tandem with a tag-a-long....and then raise you a Burley trailer.
We've got a MTN tandem and when our kids were young we'd do a setup like the above, but we'd also add the littlest dude into a Burley trailer. We could have all 4 of us on the same rig. I'll see if I can find a photo somewhere. I know it was our Xmas photo a decade ago or so.
Later,
CJB