You could say that 
It’s been on my mind ever since inline sets have been introduced.
Thanks, I haven’t heard of hime before and I will make sure to check him out.
I’m sorry, I didn’t understand the question can you help me understand it?
Not really. There has been some talks regarding multi-types and Inheritance but those are mostly considered with object manipulating rather that giving more powers to the relations. I mean, If we had multi-dimensional relations, we could achieve both of them theoretically but not vice versa.
I fancied creating a request for it. But I’m not sure whether devs would be interested in it. Should I? @Angelo @ignatovv