I would have the logo be an AutoText entry saved in a local Global Template.

Then use an AutoText field in your header for the logo.

Each branch would have its own AutoText global that could also contain the local address/phone email information.

Your templates then use these to give a local flavor to documents created based on them. You would probably want to have an AutoNew macro in the templates that would refresh and then unlink the AutoText fields.

Note, you asked about a document. I am talking about templates. What you want is a template.