Yup, trailers or cargo bikes. On casual group rides we often have a few parents and grandparents show up with kidlets over toddler age in tow -- including towed by recumbents -- or riding the back of cargo bikes with handholds and footrests.
I have a comfort hybrid with a long wheelbase, built pretty much like a Yuba, with massive, thick, stiff aluminum frame. All it needs is a comparably sturdy rear rack, and foot pegs.