I’m not quite sure why the forum software decided that your last post was spam, but I’ve restored it now.
To be honest, I’m not that surprised by their response. I don’t think they really want to set fares that are only possible on occasional days in a year. I’m also not convinced that setting an emergency OSI on its own will have the desired effect.
The South Hampstead to Swiss Cottage issue is part of a different problem, showing interchanges that don’t join journeys together on the tube map and carriage diagrams. I’m about to request some information about usage of four of those pairs, along with a pair that isn’t shown on the map but is walkable in about 5 minutes. Watch this space for more.