I'm looking at pushing out a new table to be Synced to my Mobile Users. Currently we have them download an empty clone of the file for their local copy. 

Do they all need to update to latest version of the empty file before I update the MirrorSync client to include the new table?

My concern is that if I make the update before everyone has the new file, then they will not be able to sync properly. 

The answer to this question is: without all of the proper syncing layouts the sync errors and nothing is transferred.

The Mobile users must have the latest data file before changing the sync settings in the MirrorSync Client.

Hello,

The tables that are included in a sync is the intersection of the tables checked in the MirrorSync configuration and the tables specified in the MirrorSync script of the offline copy. It shouldn't matter which change happens first. Only tables specified in both the MirrorSync configuration and in the MirrorSync script will be synced.

If the MirrorSync configuration specifies 10 tables to include in the sync, and the offline copies written in the MirrorSync script only a subset of 6 from those tables, then syncs between those offline copies and the hub will include only those six tables.

In your case, all offline users will still be able to sync, but they cannot sync info with that new table. Although the table may be specified in the MirrorSync configuration, users will not be able to sync with it until they update their database to the new version. Once they update their database version, and the MirrorSync script in their offline copy includes the new table, then they will be able to sync that new table.

I hope that answers your question. Let me know if you have any questions.