I do not understand your question, what you mean with "via one throttle"?
Anyway hope this helps:
The Kelly controlers KLS series can use a hall sensor throttle or a potentiometer as throttle, either for acceleration or brake signal.
You can find in this tutorial how to setup each one: https://youtu.be/A_si4IfU5so
i plan on building a 4wd cart with 4 brushless 205 qs hubmotors,
and i could not find anything in the manual of the kelly controller on how to wire them together so that they are all being controlled by one singular throttle input.
I have not done that before, but I think that the most reasonable way will be to:
1- Join all signal ground of the 4 controllers PINS number 20 I believe.
2- Use one of the 5V feeds form one controller for the throttle, PIN number 4 I believe.
3- Split the signal output of the throttle to the 4 controllers to PINS number 3 I believe.
If you are going to use variable regenerative braking do the same but use the 5V feed from another controller, (Not the same one used for the throttle) so you split the 5V load.