The way I do this is to have the information saved as AutoText or some other building block stored in a
global template with a different template on each user's computer. Then, use an AutoText field (which works with any building block) to display the information in the letter template.
When a new document is created based on the template on that computer and print preview is run, these update with the information from the global template's entries. You can put such fields in any templates and it will pull the information.