...
just a, maybe stupid, question but how do you find out these correlation between accounts?
Id there are ones.
Just interested in general and not related to this issue.
...
You know the Sherlock film: "The Hounds of Baskervilles"? [1]
"Oh, Mr. Holmes, I would love to tell you, but then, of course, I'd have to kill you."

We just can't tell all the secrets of finding links between individual user IDs openly, because if we write it here, all the spammers and scammers will read them too and they will care about those little things that are now linking together their accounts...
[1] Source:
http://allthetropes.wikia.com/wiki/I%27d_Tell_You,_But_Then_I%27d_Have_To_Kill_You