I smell Blood
Although the Travellers and Shelter Officials didn't know who they worked for, they knew who to report to. And that was a young man who went by the name of Taz. He had been there since the shelter had started and was in charge of distributing the funds and assigning roles to everyone.
Of course, as time went on, Taz was left with fewer things to do as he delegated the roles and the shelter grew, but still, everyone in the shelter knew about Taz.
It even left the others who were there form the start to claim this was all his doing, even though he insisted he wasn't the one supporting them at all. They still had a sneaky suspicion it might have been him, so they treated him like some mayor of the shelter.
Because of this, it was easier for Taz to request specific items and to get what he wanted. All information would eventually pass through his ears.