Mocha Pro insert object resize over time

Hi:
I am trying to insert a video element over a book cover. I am able to track the background movement with no problem.
However, I want the new book cover to change size over the course of the move, so that the cover will be larger than the book when the move is over.
Whenever I adjust the first keyframe of the insert element to fit the book at the start point, the last keyframe also adjusts (I am certain not to use the Ü option).
Is there a way to add keyframes for the Insert element so I can start at one size and end at another?
Thank you.
Ed