Yeti phase coupling and safety grounding

I am considering getting two (or more) Yeti1000 for powering a live stage.

Is there a way to slave the inverter of one Yeti to the other so the electricity from both is in phase?

For sound amplification, it is important that the phase of power sources be the same. e.g. the power for all guitar amps and the power for the main PA system be in phase.

Second issue is that we would be plugging in equipment that artists bring. Most artists' equipment is in good condition, with no internal faults, but it is a known issue that if the guitar amp the artist brings has a short, it can cause a current when the guitarist touches a microphone connected to a different amp.

When powering the stage from the grid, the solution is to provide a common ground. The current caused by the flaw will go though the ground rather than the guitarist. Can two Yeti's be set up to share a common ground?

Thank you.