how to keep the dtds locally

You can create a custom directory on your local drive that mirrors the folders from the custom directory in the Arbortext Program directory. Then you can point to it and other directories such as your base folder using the environmental variable APTCUSTOM.

This what we do to point to a central location. You could also store the dtds and acl in the proper custom folder inside Arbortext in your programs directory if you have access to it.