If you have a contact that works at multiple sites, create the various Facilities where this contact works at. Add them as a Contact (with relevant demographic information) to each of these Facilities.
This is where having a Facility Name is helpful.
For Example: You would like to fax a document to Dr Gregory House at ABC Clinic. Dr Gregory House works at two facilities, ABC Clinic and InputHealth Clinic. When you search for Dr Gregory House' contact details, within your account, two Dr Gregory House's appear. Both Facility Names populate below his name, allowing you to select the correct fax number.