Multiple SITL instances

Hi everyone,

I am launching multiple ArduCopter SITL instances (separate executables) using different SYSIDs and instance numbers.

My goal is to place the drones in a specific formation (e.g., a 2×3 grid with 10–20 m spacing) instead of all appearing at the same location
So may anyone tell What is the correct way to spawn multiple copters at fixed offsets from a common origin?