Without going into details, this is not really how the program works. Syncthing is all about decentralised synchronisation, which means that there are no “masters” or “slaves”. All devices are basically equal, and there is no central management that would dictate how other devices should work.
That said, your explanation is somewhat vague though. Have you actually tried to set Syncthing up the way you would like it work? If not, then I would suggest to give it a try with a test configuration first, and then see whether it can perform the task at hand, or not.