I ended up on my wife's bike again after she toppled over on it coming to a stop at a badly placed motorbike obstacle on the cycle path, with N°3 child in the childseat on the way to the beach. After this unfortunate but not too serious accident she asked for a swop to the Yuba and that was it. She finished the 20 Km of the ride with child and beach gear easily. She rides a hybrid with 700 c wheels which places the centre of gravity high up. That with thin tyres, a child perched up in a child seat over those tall thin wheels makes for a top heavy bike that whips along, but understeers, and is not as stable as a 26 inch bike. It really wants to fall over when loaded anytime you take your rear off the saddle. The frame might be a tad too big for her too, with these big wheels. The Yuba even with a larger child, beach bags, with its smaller wheels and lower centre of gravity makes for a safer ride and a bike that goes round corners... even if slightly slower ! We saw a lot of rabbits and partridges on the way back, but they were too quick to catch on the camera.
We will start looking for a replacement for the hybrid as she uses this bike every day and there are probably better solutions out there.