Do you want the salesman to enter orders on his laptop as he makes them and then import those records into the main database when he returns?
Import records can do this.
If this is what you want to do, where, precisely, are you encountering a problem in setting this up?
Setup your database so the salesman can access it on the road? Would require an internet connection for the salesman.
Would require that you turn on Sharing on the hosting computer in the office.
And adding a port forward to your router, to direct FMP inquires to the hosting computer.
The salesman would then log onto the database with the "Open Remote" command in the File Menu.
Works great ,