Multiple company support. Help!

I'm looking for some advice on how to handle the following scenario:

We support multiple clients - mostly banks and credit unions. We could receive an email ticket from multiple end-users, all tied to a single company.

How would I tie multiple 'requesters', to a single 'company'? I want to be able to query to get all tickets for ABC Credit Union, which could include requests from a variety of individuals.

I have not found an efficient way to handle multiple requesters for a single organization. Is this possible with SDP?

Credit Union A
      Requester 1
      Requester 2

Bank B
      Requester 1
      Requester 2
      Requester 3

etc.