ALL radios are capable of controlling multiple planes. (Ask anyone who's been "Shot Down" when someone at the field turns on a shared frequency transmitter without the pin). You just have to set the non-computer ones up carefully. That's why computer radios can spoil you. If the servos are zeroed out and the end-points are controlled with the plane's linkage and not the transmitters internal endpoints you just need to buy a receiver for each airframe . . . or even swap out one receiver in multiple bodies (done that, too).

Ah, the old sliding servo tray mixers. Used for "V" tails, too. Back when solutions had to be elegant instead of programmed. Another beauty was the three-legged "trident" ball-joint articulated servo arms that had an aileron on each of the outer legs, and the center arm hooked to a seperate servo.