That’s unfortunate.
Instead of requiring an insurance selection or defaulting to one specific instance, perhaps they could have a handful of moderate/large instances that the app randomly selects between when a user signs up. That would spread out the signups from people who don’t understand the instances.
Or the comment sections could just be merged together in the client view. Each thread of comments would belong to one (and only one) instance, so it shouldn’t be difficult to merge those lists together when presenting the aggregate view to the user.