In the case of Fair/Foul, the position of the ball when it is first touched is the only thing that matters. If the ball is over foul territory when first touched, it is a FOUL ball, if it is over fair territoory, it is a FAIR ball. The position of the fielder who first touches the ball has ABSOLUTELY NO BEARING on the fair/foul call.
There are online rule books at
www.pony.org and
www.playnsa.com. Look in the Definitions section.