[Suggestion] Add Flag Areas

Since sub-flags already exist, I don't know what to call these. Don't worry, I have looked up all of the flags in the wiki and this doesn't exist yet.Let me explain.
I wanted to have a grief party on HALF of my residence, but when you set a flag on your res, it sets it for the entire residence. Can there be a command- setting the area of the flag if you don't want it to be set for the whole res? It should be like the /fill command. Basically, you set the flag area in a box.
Lets say I wanted one of the corners to be at (-35, 50,399) and another at (-50, 20, 400) The command would be something like this: /res setflagarea destroy -35 50 399 -50 20 400. This will make the flag only in that space. Then, once you did that, you could assign the psets to the players you want. For example, mob arena has its own "flag area."
I hope you understand and leave a comment below.

EDIT: found this while looking at flags, can a contributor fix this?

It should be #1001 I think. =D

If it's not too hard to code (I've no idea) it would be cool.

+1

Also would make "renting" space way more practical, which might pep up the economy...