Privacy - disclosing mutual customer to Brinks?

We have received several armored car deliveries from a fast food restaurant. The teller neglected to collect Brinks' EIN number for the CTR filing so our banker called to get the EIN number via phone and they refused to provide it - but said the driver would give it to us in person at the next delivery. The driver (forgot it) failed to provide us with Brink's EIN number during the delivery yesterday. I advised the branch to refuse deposits until it was obtained (bold I know). Today, the copy of Brink's I-9 was provided and they (Brinks) is now asking us for the name of our customer that we are using it for and my branch president is asking if he is able to provide it - they are a mutual customer to us and Brinks - but I have never had this question posed to me. Thoughts on breach of privacy? The customer is contracting Brinks to deliver the deposits to us so they know our customer and that our customer has their accounts here. Brinks delivers for more than just this customer for us so perhaps they are looking to keep track of who they are providing the information for? I have an idea of what I think the answer is but appreciate all points of view to consider - thanks!

I wouldn't have any breach of privacy concerns about it. Brinks already knows the names of their customers who are also your customers, so you are not giving them any information that they don't already have.

That was my line of thinking also but I'm on my own compliance wise here and it's nice to have a corroborating voice with me. Thanks!