which Layers to convert to Smart Objects in a file
I've recently been introduced to the benefits of working with Smart Objects and watching videos on youtube, but haven't found the answer to this question: per the image below I need to play with the exposure and/or smudge the line down the center of the image where 2 images were tiled together. I can't use the smudge or blur tool here presumably because I need to do so on the intersection of 2 Layers. Therefore I need to (1) merge Layers or (2) create a Smart Object and/or Filter to do this effect or (3) create a Smart Filter and use Camera Raw Filter to darken the exposure on the left side or a combination of the above. So my question is which Layers do I convert to Smart Objects? All Layers or just the ones that would apply to this area of the image? Since I'm kind of not sure of what next steps will be is why I am asking. Thank you.

