Ranjo, way to stick to your guns. Maybe your partners should start attending this forum.
The closest reference I can find in the Case Book is 4.4.1 - A2 catches the ball while both feet are on the floor, with one foot on either side of the division line. A2 lifts the foot which is in the frontcourt and then puts it back on the floor in the backcourt, IT IS A BACKCOURT VIOLATION. When A2, WHILE HOLDING THE BALL, lifts the foot which was in the backcourt, the ball is now in the frontcourt. When A2's foot then touches in the backcourt, it is a violation.
The key is as you said "holding the ball"
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“The foolish and the dead alone never change their opinion."--James Russell Lowell