Well, no, you can use a Y connector for the ailerons too. So, you can feed your ailerons to the aileron channel using a Y cable to the two servos, and the AUX1 channel for the Flaps also using a Y cable for that.

The aileron operation depends on how you connect your linkage as do the flaps. My drawing I added to my reply above shows how this is done. I've done it on two aircraft and it works just fine.. even though I never use the flaps.

CGr.