This exact subject was brought up at the Warhammer FRG board. The answer from FFG was it does not take a maneuver to disengage an Ally. The Star Wars Edge of the Empire Beta (pg. 131) also states no maneuvers are required to disengage an Ally. I am assuming this as not changed in the Core Rulebook (Sorry, don't have my copy yet!)
So the answer to your question is: It would only take 1 maneuver to go from an engaged Ally to medium range. You would be going from engaged to close range (no cost), then from close to medium range (cost 1 Maneuver.)
Hope that helps!
Edited by ValiantOne, 06 July 2013 - 09:56 PM.