Total use including diverted but not solar (see MySolar Divert App Setup)
Yes, sum all three (and possibly the 4th in the office too IIRC?) this gives you “grid” which will indeed go positive for import and negative when exporting during times of excess PV, so you add a “allow positive” process and log that to a feed as “import” and then use a power to kwh for “import_kwh”.