FYI, I think using the term ‘multi-relation view’ might be misleading for some people.
I suppose you mean the option for multiple (tabbable) relation views, available for collection fields.
I don’t think we use the term ‘multi-relation’ except in relation to the polymorphism that Highlight support.
Perhaps, instead of proposing a specific solution, you want to elaborate on a use case that you want to address, since I feel it might be solvable in many different ways.
(I did note your other post, so I guess it’s related, but I can’t help but wonder if Daniel’s idea is a neat solution)