My question is what kind of support does ES offer for synchronizing any changes made to the data once an internet connection is re-established? 

For example, if the salesperson changes a customer's phone number while working disconnected, how does this new phone number get applied to the main database when the salesperson reconnects to the internet? 

Are the synchronization tools built in to ES, or would I have to write it all by hand?  At reconnection, is there an opportunity to open both the local and the central (ES) tables simultaneously and do the needed comparison and updates?

TIA,

Larry