2.7 Swarming and alternative Mavlink System ID - athertop/MavLink_FrSkySPort GitHub Wiki

The developer Clooney82 (Jochen) raised a good point - should you amend the Ardupilot Parameter SYSID_THISMAV (Ardupilot parameter info here), as Jochen was required to do as part of his swarming project, then also ensure that you change line 121 in MavLink_FrSkySPort.ino to reflect the system ID of your craft.

#define AP_SYSID 1 // autopilot system id