You need to go find the record drawings and find the Riser Diagrams for either each building or the sum of all the buildings.
If not available or incomplete then, IMO; One will need to do a total survey to reflect the total Panel system from the street side supply to the string of loads to the down line load in respects to each panel.
Having said that! It can be done in-house, with the proper PPE gear, with-in the limited windows of ?Down Time? for product lines, etc. Or can be done when cold!
A Riser Diagram reflects each panel size, the circuits that supply it, the branch circuits that run out of it and branch / distribution to additional down line systems (panels).
Each Panel (will/can) create its own panel schedule, an example POCO trannie outside, 4000 Amp six throw in one building to six panels and split out from there. All these need to be ID?d.
The simple answer is to break out the Lighting panels and the Power panels. I?m sure each building has a name or a personality! U can use that reference with letters to suit.
From the top U have the MDP- Main Distribution Panel to be a server of your six other panels, or trannies. The key is to have the numbers or letters reflect your exact location, per the building!
Or the Kiss principle of Trannie, XFR-01, LL01, PP01? it should be exact and a little thought out, hope this helps.