I have a Tekno, not that it matters, that I would like to have a receiver for the kids radio, and one to also use with my radio . In other words switch radios back and forth with out having to pull anything apart. I guess best option would be to just upgrade the kids radio. They are two different brands. Thanks for any feedback

You could, you would need to install a switch inline with the power from the bec. Also several y harness would be needed. One for the servo and one for the esc, this would also take up alot of space. Just put the red wire from your bec into a 3 position switch and have the 2 legs one goes to each receiver.

The easiest way to do it is to get traxxas
Get the latest TQI MODEL 6509R: trans and reciever kit
and a 2nd reciever

recieverhttps://traxxas.com/products/parts/radios

That way you can use any transmitter with any car and not have to worry about what drives what .

another problem to tackle will be getting the trim set for both brands of radio... if it were the same brand I could see this being more practical, but I doubt the ESC will hold the calibration sequence, etc... good luck!

Very good point, maybe if you had 2 of the same radio? That would minimize the variance

Easiest solution would be to save two different models on the radio.
One model for you, one dialed down for the kids.

What problem are you trying to solve? You certainly could mount the two receivers and do some fancy wiring and switching to make it all work but there is likely a better solution.

I use this solution to slow down cars for my son, but i'm guessing the problem he has is the kids use a certain radio that is easier to use for them?

I would just equip the two receivers with velcro tape, so they can easily be switched out. Just pull off the receiver and insert the two connectors, should be quick enough. I would prefer this myself over wiring up some monstrosity of y cables that allows either to be selected.

Another idea : mount both receivers, and if you have a receiver box, solder up a homemade 4 port connector bay hooked up to both rx and coming out of the receiver box. All you would have to do is swap the two connectors, which now can be done outside the rx box, and still protect the rx's. But i guess i'm back to lots of wires again, with less ease of use!

With an advanced radio with the subtrim, trim and D/R settings you could calibrate the transmitter to the needed setting, looks to me no problem.
Most simple is use Velcro on the receivers for an easy mount and take out and replug the 2 wires.