Blend / Merge photos with same background together

I have simple photos all taken on the same dark grey backdrop. I'd like to merge 3 or 4 of these images together, removing the line between so it looks like they are all one photo. I've tried quite a few different ways to do this; the "remove background" worked well, but then I lose the shadows and it's time consuming to put the shadows back in. I've tried photomerge but doesn't work. I've tried laying the photos out across the artboard side by side then 'merge visible' and use different tools to blur the lines but doesn't give the effect I'm after. Any ideas? Photo attached of what the images look like. Thank you