Using 1 throttle for a brushed controller and a brushless controller at the same time

I am trying to find out if I can parallel one hall throttle for different kinds of motor controllers at the same time. I have a 48v Brushed Motor Controller(hall sensor, 800w - 1500w, 50a max)hooked up to Unite MY1020 (both from TNC Scooters) and a brand new upgraded 48v Brushless controller (350w, 15a max) from E-Crazyman hooked up to a Ananda 198 Hub Motor (oem: 36v, 250w, 15a max) and have a simple 48v w/led thumb throttle from E-Crazyman hooked to the brushed controller. Currently I have the 48v on my right side and the 36v OEM half twist for the hub flipped around on the left. It works but it a pain in the ass or more appropriately, the wrist. I already have carpal tunnel from doing so much EV reasearch. I swear its not from porn. Back to the point. I want to use one thumb throttle for both motors and hook the motor contoller inputs to a relay bank controlled by a 3-way switch so I can use one or the other or both at the same time. I also have a small 6v battery wired to a BOOST button that controls an existing relay bank for increasing voltage. I havent broken or burned anything yet (knock on wood) and don't want to, so your help would be appriciated.

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