Please Help: Drag and Drop Pictures in the Same Spot

Hello,

I'm trying to find an easy workaround for a live-stream. I want to easily swap images from one to another. Imagine it like a VS screen and I just want to easily swap out the character on each side with other characters.

I tried to set up a slide-show where I could just drag the image of the character into the folder, but every time I try to replace the image, the slideshow source doesn't show it. I could do 2 image sources and change the location each time, but it seems messy too to do it every time. I also tried the photoshop route, but it's too fiddly as the photoshop window could easily change in frame size.

Any other idea I could try or do you know any software that would let me easily swap pictures out without affecting the frame?

Thanks!