It would be nice if there was a way to add a template to an existing project and to specify that the template should use existing tables and fields.
It would nice if the form of a wizard, where it shows the tables that are being created and gives you the options to specifiy an existing table. If you pick and existing table, then you can specify whether it uses existing fields, or creates new fields on a field by field basis.
Basically, you fill out a form, and it configures it for you.