I think it’s been demonstrated on this thread though, that this is overwhelmingly an imagined issue. No one has provided a named example of “obvious connections” being explored “at the expense of other equally as important” contexts on a permanent basis at an NT property. It was claimed this was the case at Penrhyn, but other aspects of the house’s story were very much still displayed.
Temporary exhibitions may be a source of confusion/contest. If someone visits a property/gallery during a temporary exhibition, such as at Penrhyn, or at the Fitzwilliam, or during the NT’s “Pride and Prejudice” programme which ran in summer 2017, then they may gain the impression of displacement. But, the chances are their preferred “context” will get its day in the sun too. Not every theme has to be played out all at the same time, and, as we increasingly realise history is not singular, but many “histories”, then revolving themes make sense alongside a foundation of basic information about the property.
Also, consider this: other “contexts” will likely have been explored over decades at a property. Why shouldn’t balance be restored by prioritising giving some new contexts their moment in the sun?
As I mentioned above, I think one major issue is that many people don’t understand that slavery and colonialism are their histories too, rather than some niche minority/Black/SJW” history. And, it’s a topic that has shaped huge swathes of the world and continues to do so today. Often it’s of more historical importance than alternatives, but people don’t know this (yet).
Regarding your local gallery, is the exhibition temporary or permanent? What’s the theme? What type of work and artists are on display? To reply I need to have some context.