Joystick and throttle problems

this is my first time in every thing (MP,Pixhawk and UAVs) I’m rely thankful for the decoctions and the solutions given it helped so much in my project only for one problem the joystick and the throttle are two separate units with deferent USB ports on the PC and they are showing up as two different joystick units in Mission Planner where you are only able to choose one. So I can either only use the joystick or the throttle to control my plane…
Is there a way to use more than one joystick unit to control my plane?
Looking forward to your answers