I am staff on a few trackers ; and yes when we find ratio cheaters and the like we send all details to a list of trackers for investigation, on the list is HDB, HDT, PTP, BTN, MTV, PHD group, Blu, AR and a bunch of others .

This is done for bad cheaters and traders/inviters only, unlikely to be done for members on the invite tree, but would be done with the invitee in this case.

But main tracker I work for is going to limit number of invites available to be issued to X invites in a year. This is largely to stop traders/sellers.