At the present time, Zumero doesn't allow sync of a partial table. If we sync only part of a table down to a device, then SQLite doesn't have the ability to enforce a UNIQUE constraint.

SQLite does have excellent support for using multiple database files together (using ATTACH), so there is plenty of opportunity for setting things up to ensure that each device only syncs the data it needs.

Just subscribe to the data that you care about. For example, Meteor.js does exactly this by giving each client a slice of the production db locally, but only the part that they subscribe to.