From the papers I have read about the landing sequence, I see the combined descent stage/lander descending to about 18.6m at 0.75m/s down when the rover is separated. The rover then descends at about 1m/s to the end of the 7.5m bridle. After that, the descent stage continues to drop at 0.75m/s until the rover contacts the ground. Once the rover is supported by the ground, a lot less thrust is needed by the descent stage to keep a constant speed. It takes about 1 second for the system to realize this, and another second while it cuts loose before it starts to ascend.
So while the rover lowers to the end of its bridle, what is the descent stage doing? Is it still descending at 0.75m/s, meaning the rover is descending at 1.75m/s relative to the ground? Also, when the rover is in contact with the ground, is the descent stage still descending at 0.75m/s? Does this bring it 1.5m closer to the rover before it detaches and flies off?
I'm trying to put together a timeline for one of my animations.