Stuff like THIS is the reason Housing is a Joke -- SE please do something about this!

[Jojoya]

As for addressing the Multi-buying option, it'll be really difficult cause there are some people who will buy more than 1 account and will try to buy the entire ward. Instance housing is the only way to prevent this sort of abuse but instance housing is unlikely to be done in FFXIV. Only thing they can do now is just adding more ward, which only extends the problem rather than solving the problem.

We have instanced housing. All interiors are instanced whether house, apartment or FC chambers.

It's the exteriors that aren't instanced and that is causing the problem. SE just needs to extend the instancing to include the exteriors, using the placard as the portal to multiple player plots at that location just as the apartment building door is the portal to multiple apartments.