Control (out) or not?

[DaveASA/FED]

Here is the play: R1 rounds 3rd heading home, F2 receives ball and tags R1 prior to reaching plate. BUT, as she is completing the tag on the up swing (swipe tag) the mitt hits the runners knee and the ball falls out as she is bringing the mitt up. To better describe the situation, F2 was pulled to behind LH batters box to get throw, she is coming up to make tag and swings from her R to L contacting R1's outstretched foot up her leg and then as she is coming up with it R1's other shin/knee contacts the mitt and the ball comes out.

So now the question: Do we have an out? How do you determine how long she has to have control of the ball before calling the out?

I see it as control has to be maintained until completion of the play. Meaning in this case until she brings the mitt up to complete the tag, and / or tries to make another move with it. A fellow blue thought the contact with the lead foot and leg gave her the out, and the following knee / shin contact that knocked the ball loose didn't matter. What say you all?