On 29/01/2018 08:27, MM wrote:
Could the component parts (bell push, chime unit) be modified so that
several chime units would respond to the same trigger code?

It depends. Some of the cheaper ones may be hard coded and not possible
but decent ones should have this facility.

We have 3 rather elderly Freidland Libra sounders distributed around the
house which all respond to a single bell push, The push button and
sounders each have a small block of 8 DIP switches which can be set to
pair them or to avoid conflicts with neighbours' units. An additional
switch in the push can be used to select between 2 different sounds if
you have pushes on 2 doors..

--
Mike Clarke