Unique Sends

Hey All, 

I'm trying to understand how best to get number of unique email sends for specific email campaigns (the campaigns may send to the same recipient multiple times which is why I care more about unique than total). My initial assumption that I have been using is to find either the number of unique recipientIDs or broadlogIDs from the nmsbroadlogrcp table that are related to email codes from joining with the nmsdelivery table. The numbers I get seem logical, but I was wondering if there is another accepted way considering the delivery table does provide email send metrics but they seem to be more in line with total emails sent rather than uniques. 

Thanks for all the help!!