[gemadon]

How do you do it? Make 2 houses with 1 interior? And how do you use virtual worlds, what is it for?

[Correlli]

Just add the same coordinates and same interiorid for both houses. And virtual worlds are useful in house-system.
If two players are in the same interior/place and if player1 has virtual world different than player2 then they can't see each other.

https://sampwiki.blast.hk/wiki/SetPlayerVirtualWorld
https://sampwiki.blast.hk/wiki/SetVehicleVirtualWorld