There are very few cases where Coordinator / End Device settings need to be used when working with Series 1 radios. As MVUT has stated, you simply need to make sure each radio has the same CH and ID parameters.
Because you are using API mode, you can set each packet to be either a broadcast packet (everyone hears it and passes it out the UART) or a unicast packet (everyone can hear it, but only the specified radio will send an acknowledge back to the send and pass it out the UART).