Why would the manufacturer install 3 200 amp panels and one 100 amp panel if they did not intend them to be used. I would contact the manufacturer and get their reasoning for these panels.
Check with POCO also and see if the service is maxed out for 200. If not you may be able to make the tenants panels 100 amp along with the owners panel. But I would still question the reason 3 - 200 amp panels for this load.
If they are all together, bond all panels to the electrodes and piping and wire each panel for the current of the main breaker. Do some reserch before proceding.
