I just installed a wall remote and all works well. If I buy a hand held remote, do I need to add another box to on the fan or will the new hand remote know and talk to the existing box.

Thanks

So the switch on your wall is a wireless remote, correct? Most of those types sit in a cradle and are meant to be lifted out to be hand held. If you get another handle held the chance is zero it will communicate with your exiting fan. Tell me more