Ok I actually just worked it out.
It’s not super simple, but it get’s the right answer with this example data.
I’ll add the file so you can have a look through.
Let me know if you see any issues with it.
The ultimate formula could possible be integrated into one function. Maybe have a look at that.
I’ve just spent a significant amount of time on this one so have to move on.
Attached
Rank Unique.pbix (34.8 KB)
Chrs
Sam