RE: 4 Aileron Servo Set-up
You could use a wye for both upper and lower servos on each side of the model, only.
I not much on JR TX's but there is a mix, factory default for the aileron dual servo function as is for the dual elevator servos. When you program your own mixes that are many things that are often over looked that effect equal speed and travel. Use the factory mixes!
Since the ailerons surfaces/servos are not interconnected you can simply use a wye for the left and right aileron control. Center each surface with the radio system on and then check travel. I'd suggest getting a control throw meter to set the surfaces up. It's important they move equally in all directions. From here you can adjust each control horn and turn-buckle to your needs.