I am creating a module for synchronizing between a LAN based application (DBISAM database) and the Store module - version 2.01.46.  For ease of setup I'd like to be able to pull information from a table in this external database and use it for the Categories in the Store.  Since I won't be able to use the same ID fields in both databases I wanted to create either a separate table that translated the ID from the external database table to the Store_Category CategoryID OR better yet add a field to the Store_Categories table for the value of the ID in the external database table.  I do NOT want to destroy the integrity of the store code so as to continue to be able to take advantage of future changes to it.  So.. would it be best to keep my own table with the two keys in it or would creating an additional SQLProvider file ALTERing the Store_Categories table by adding a new field allow me to maintain the integrity of the Store while making the additional piece of information I need for synchronization available to me.  Guidance would be appreciated.