At first it may sound a little silly, but that is exactly what happened with his thread, with confusion over the history of North Roskear.
Take this as a hypothetical situation, say in five years time, Crofty are working, someone is lucky enough to get a load of pics in different parts of the mine, say Parts in East Pool, Old South Crofty, New Cooks, Roskear and Dolcoath, where do they put them? In the individual mines or as one.
Its worth remembering its easy to know where you are on surface, and still get it wrong, what chance is there underground?
I have access to pictures of East Pool underground, taken in the 1980's, if I could put them on heren (I can't because of copyright) would I put them in Crofty or East Pool?
The pictures of North Roskear that started this is an extremely good example: -
The site is in the North Roskear Sett (It was something else prior to that), the Shaft was initially sunk after the Sett had been taken over Dolcoath and then the shaft was deepened, new headgear and winder installed by Crofty after they had taken over the Dolcoath Sett.
So is it: -
a) North Roskear Mine
b) Dolcoath Mine
c) South Crofty
As far as I'm concerned its c), but by your argument its a) Others would consider it b) as it was sunk in the ownership of Dolcoath.