How you would go about adding modules to the PLC database depends on whether you're using parametric or fixed-unit plc symbols. In my opinion, being able to do this is an essential skill in ACADE, most especially when it comes to parametric PLC symbols. The software provides the tools you need to add products to the databases. For this reason, you may want to consider keeping a backup of your databases so that in the event of something bad happening, you don't lose all the additions you make over the years. It is up to us users to add new products to all of the catalogs.
Autodesk leaves it up to the manufacturers to submit new product data on their own, and basically no one does. ACADE's libraries are very rarely updated.