If I'm not mistaken, 99.9999% of all pro golfers mark their ball. If they hit an errant shot into tall weeds or a hazard, they can identify their ball in the event there is more than one ball lost there. Hitting the wrong ball is a penalty. As far as using the mark to line up a putt, it is really no different than using the manufacturers markings for the same reason. And as far as her cheating, marking the ball is allowed, so there is no unfair advantage that isn't available to all golfers.