If you want two-way communication, you will need to do things sequentially, and that will probably be quick enough for visual "same time"ness.
If the EL controllers don't need to send anything back, you should be able to send one signal to all three receivers at once. If the nRF24L01 modules won't work tat way (ie. if they need to handshake with the transmitter), then a simple 415-433 MHz transmitter and three receives willl do it.