Starter relay question

I'd begin with pencil(s) and paper and by checking four things:
Alternator output, Battery positive, and the alternator and starters to determine what tiype of wiring arrangement each needs.

The first two are the power supplies. Follow those wires to each and every place they connect. There will be one or more junctions to the main circuits.
From there identify the main circuits. There must be at least one feed to a ignition switch. If its a factory multiswitch, then one feed. If it has push button start or other arrangements, then multiple wires. There ought to be one feed to the fusebox, maybe another to relays if added, a feed to headlight switch B1 (if factory headlight switch), and one feed for a horn relay.