Linking a moving image to another image in Premiere so the second image also moves

Hello!

I am relatively new to the world of Premiere. I am making a video that is basically a slide show of still images using ken burns effects on each one. I would like to keep everything consistent with consistent motion. Each of my photos started as different sizes, so zooming at the same percentage has inconsistent results. Rather than throw the photos all into photoshop to make them the same size, I am trying to use a trick I heard about. I am trying to add a layer on top of each photo that is a smaller transparent square which is the same size throughout. Then I will just change the size of the square to keep things consistent. Ideally, the moving square and the photo will be linked, so as the square zooms, the photo zooms.  But I'm having a hard time figuring out that linking. I thought I could do it with nesting, but I don't think it works. I've also watched tutorials on masking, like blurring someone's face who is walking, but I don't think that's the same thing.

Any ideas? Is this idea even worth pursuing? Do you have another strategy for keeping moves consistent on different sized images?

thanks!