I think you have two choices:
1. Distribute the addin to the clients and help them install it in their startup folder
2. Bring all the "contracts" into a single template (by saving each as a quick part) then either:
- teach the users how to select the relevant contract from the quick parts
- add a startup macro that displays a userform which lists the available quick parts and lets them choose one to insert.

I would normally do the second option because I don't like having progressively bigger and bigger sets of files where minor edits need to be repeated in all the files.

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Andrew Lockton
Chrysalis Design, Melbourne Australia