It might be better if you can scrap the total unused airdropped sMerits into two parts:
This isn't really possible: theymos airdropped 600k sMerit, but it's not published how many each account received, and Merit source amounts are more or less a secret.
I don't remember exactly but I read somewhere months ago that thanks disclosed that the rate of sMerits airdropped depends on both ranks and total active time within last one year before the launch of merit system.
Lots of users [heroes] complained about they got only 500 merits, then theymos decided to make additional airdropped merits to Heroes who have total active time above specific threshold.