6000xp Parallel Setup - Split Phase Imbalance Detection Relay

I am wanting to setup my 2 6000XP inverters in parallel with load output going to a combiner subpanel.  I then want to have a phase imbalance detection relay with breaker shunt between the combiner subpanel and a load panel.  Has anyone done this?  If so what relay and shunt/breaker did you use?  This would protect my devices connected in load subpanel just in case inverters got out of phase for some reason or another.

Thanks