The majority of two-child cargo ebike setups that I've seen in DC are the Tern GSD followed by the RadWagon (forgot to mention Xtracycle in the prior post, there are a few here and there). Aside from the UrbanArrow/front-bucket bikes and people in the Netherlands I haven't seen too many people put a child in the front on a two kid bike here, there's issue splitting attention as well as balance unless you're an experienced rider.

I have a GSD and I love it. No kids but I use it to carry a dog in each side pannier. Happy to answer any questions about the bike, hopefully someone with more experience specific to your situation can chime in about seating configurations (essentially bar enclosure vs seats I think? realized the tent fort is just for weather and needs the bars to function)