[al'Lan Mandrag]

Spoiler

The scuvs aren't a group per say- it's a derogatory word to describe someone who does the work the Thieves Guild does, without their support

That said, you can think that a high ranking member of the Thieves Guild would have the contacts: The leader, Coursan, or one of his main circle: Fervon, Thevya, Alicia and Rickard.

You know little of the players outside the Guild, but you know there are a few wily criminals who have some power free from the Guild's control.