Years ago I used multiple flash when it was with flash bulbs. No meters, no TTL etc. There was an amazingly simple way to determine exposure and placement. Once the main exposure light had been established ,usually by trial and error tests. The equivalent of determining film speed, which you should be with a new flash unit anyway. The other lights could be determined using the f stop scale as a guide Converting the f scale into feet ,if the main light is say 8 feet from the subject then 11 feet f/11 would be a 1:2 ratio. 16 feet f/16 would be a 1:4 ratio approximately. A few quick trials will establish the working values This even worked with color transparency film which had practically no latitude at all.