<...> Who were the first members that automatically gained some merit points? And how many merit points were given? Different to each merit source?
In addition to what @Harkorede stated, there were also a group of Hero Members that received 1K Merits (instead of 500 Merits) during the Merit System kick-off.
Now asking about Merit Sources here, in the same context, may mean you are mixing-up Merits and sMerits. Your first question was about the initial Merits for each forum member (awarded to all forum accounts on the 25/01/2018, who were at least Member rank or above – Jr. Members did not require any merits back then), and Merit Sources are rather more about sMerits (sendable Merits).
Merits: Non-sendable, non-reducible (except on rare abuse circumstances).
sMerits: Sendable, reducible (when sending). You obtain 1 sMerit to send to others for every 2 earned Merits (which originate by somebody sending you sMerits in turn).
In addition to the initial Merits, forum members also received a variable sum of sMerits during the Merit System kick-off (depending on their rank and activity over the prior running year). Merit Sources’s sMerit monthly allowance differs from each other, and may vary over time (whenever allowances are revised.)
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