As long as they are the same class of receiver, it will work. Even with a DX8.
By class I mean they all need to be the same speed (11/22ms) and modulation (DSM2/DSMX). The easiest way to do that is use 4 of the same. Note that each receiver will have the same channels on it, so you will have lots of unused outputs doing it this way, but there's no other problem.
If he is using telemetry he can have only 1 TM1000 in the system.
Andy