The design reminded me of a thought I had a couple of months ago. I had seen a few longish dutch cargo bikes being pedalled around with a couple of young children in the front box and thought that it didn't look very friendly for them - wooden seat in a wooden box, etc. Many parents don't cycle because they can't easily take the young children with them. Empty seats could also be used for shopping.
Ignoring the front end requirements, I thought of having configurable passenger seating for 1, 2 or 3 children, at the rear. A single detachable child's seat fitted above the rear wheel for 1 child, a single seat either side of the rear wheel for 2 children and a measure of balance, or use them all for 3 children.
Substitute the seats for boxes and you have shopping transport.