Both these devices are just a codec set, therefore transmission reliability would predominantly depend on how are them coupled in the physical layer, which depend on many factors, such as distance, interference, RF modulation and frequency, obstacles, etc...
In all RF communication link you have to provide additional layers on programming levels to deal with the risk of data loose, such as protocols with ability to request to resend command, acknolowedge reply, indexing transmission packs, error correcting algorithms, etc...
Regarding to your need of spread a command to several devices, it is plenty usual. What you should to do is assign to each device a unique slave address, that once received and corresponding to the command only that device will respond act.