multiple frequency rf module

hai,
i am designing a quiz master module to conduct quiz. I have completed a wired module. Now i need to move on to wireless.

As the local rf modules(433.92Mhz) allow only one transmittor at a time. I have decided to make one using nordic rf2401 by setting different frequency for each contestant. so i hope each transmittors operate seprately.
My requirement is to recieve all the transmittors at a time.....

Now my doubt is, can it bedecided for different frequency, it is said its frequency is 2.4ghz.

Is there any module in the market whose frequency can be changed?

There are family radio intercoms (walkie-talkie), which can be set for different channels.

I believe the channel setting is remembered when power is off.

This may or may not be the type of thing you're looking for.