Wow, you do have an interesting way of looking at photos. As can be seen in that first photo in the thread, CO drove her arms through KML's arms to get control of the ball completely away from KML, and yet you say that somehow KML was pulling down on that ball with her weight? Check that photo again and tell how many ounces KML had "pulling it down,"as you say.
From the film evidence, we know that Kaleena got to the ball a fraction of a second before Chiney, but reaching to her right. We also know that Chiney came at the ball directly under it and grabbed it with two hands outstretched above her head, and her momentum taking her into Kaleena at an angle to her rear. From the photo, we see Kaleena with her hand on the ball, off the ground, and with her center of gravity over her right foot...consequently she is unstable both to her right...her center of gravity is at the tipping point...and to the rear where Chiney's momentum is driving the ball she has her hand on.
None of this is a problem for Kaleena if she releases the ball and cedec the rebound to Chiney...alas, that is not in Kaleena's DNA, so she strengthens her grip on the ball with her right hand which is firmly attached to her 185 lb. body with the force of gravity taking it down...where it must pull the ball unless she releases it. On top of that, she is now being pulled by the ball because of Chiney's momentum backwards...this makes her not only grip the ball harder for support, but also leaves her in a position where she needs to grab Chiney's arm on the way down once she loses the ball to break her fall. We can't see her do that in the film, but it is the natural reaction of anyone falling backwards...even very young children.
And CO just had to either go "ceding the rebound" or "pull the ball toward her body" to control it? That is so out of an early Alicia Silverstone movie as to be hard to fathom. As if CO was at risk of losing the ball with KML driven toward her backside and all CO had to do was let the ball come down on her left side away from KML.
No need to display your encyclopedic knowledge of Valley Girl wisdom...this old engineer won't appreciate the wit.
From Chiney's perspective, she grasps a ball with her arms outstretched over her head (again, see still photo) that has a hand attached to it that is pulling down with not only Kaleena's full 185 lb. body weight...that she'd be exerting just by grasping the ball and returning to earth under the acceleration of gravity...but also by the added force of any attempt by Kaleena to flex her bicep and gather the ball in. The natural reaction of a rebounder in a contested rebound is to resist the forces pulling the ball away, however, a determined Kaleena who is now falling to the side and backward puts enough force on the ball to draw it down because Chiney is airborne with arms fully outstretched and so can exert little upward force in this situation. What she does do...as we see in the film...is draw the ball into her body even though her right hand comes off it...and the only force pulling her hand off the ball is Kaleena's arm which...as we stated earlier, comes off the ball and may have grabbed Chiney's right arm for balance, thus explaining her hand leaving the ball.
Look those of use who have played some BB know that there are many ways to control a rebound once you get your fingers on it, and the best way is to sweep it away from another contending player. Or if you have the chance and you have an opposing player extended, you can hook them and then drive your arms and body into them, maybe to send a message or because you know you can get away with it. This is done a lot but it risks losing the rebound because the ball is down low where it is sometimes grabbed away.
I've played, coached and watched enough basketball to understand how a rebound is gathered...and I've played enough collision sports, and practiced enough forensic engineering to have a decent perspective on the physical forces at play and the way they need to be countered. I do hope that Kaleena and Breanna are given a strong regimen of lower body work, in addition to some repetitions on how to compensate for balance issues, particularly in the paint area where big bodies are flying around.