In this design, you can’t (and you shouldn’t need to, because you’d create a new Beacon next-door).
We want players to always understand what a lock is going to mean for them – we don’t want players to see locks and think “hmm, can I open that?” and then have to interact with it to find out. A really good way to solve this is a consistent rule set per Beacon. You already know if you’re a member of a Beacon or not, which means you know instantly whether locks work for you or not. We hope it’ll be easier to understand than a different set of rules per lock (which we did consider originally, but this feels more solid).
Beacons 2.0 (not the current implementation) are going to be distributed on a grid of plots across the world. The resolution of this grid is still to be decided, but it’ll probably be something like 16x16 blocks.