Rear-steer tandem with middle child saddle I saw a bike for hire in France, and I'd like to track down more details on it or something similar.  Unfortunately the hire logos covered the manufacturer logos and the bike was locked up to others (all with the same colour frames) meaning I couldn't get a picture to show anything clearly.  And the shop was closed.

It was a rear-steer tandem, with quite small wheels (maybe 24").  In front of the rear rider's saddle¹ was a low saddle with fixed handlebars and foot pegs. This was positioned rather like the top-tube child seats common in Europe, but from the design of the child's handlebars it was clearly integrated into the frame at manufacture.  It looked suitable for a tall adult at the back and up to a short adult at the front. All three sets of handlebars where slightly swept-back flat bars.

This seems more sociable than putting a rear toddler seat on a tandem (where they can't be heard).  It would also have a higher weight limit and allowing panniers. 

The only current manufacturer of rear-steer tandems I can find is Nijland, and they are all step-through (so no top-tube to put the child seat on).

¹ I guess I should call it the captain's as this is where the steering handlebars are.
While I never identified the exact bike, some similar bikes (rear-steer tandems and triplets in a variety of adult/child configurations) are made by a company called Amsterdamair.  They're based in France, only a couple of hundred km from where I saw the bike.  I suspect it was one of theirs though not quite a standard model.