Photoshop :: Modifying Linked Images

I'm making a booklet (in InDesign) that will have a few pages filled with collage-type visuals that I'm planning on making in PS. I'll be using a few low-res images that a photographer has given me but hasn't yet retouched, converted to high-res nor color profiled - but he will need to see my collages before being able to retouch them. I was wondering if there was a way to relink placed images in PS the way you can in Illustrator, but after rasterizing the images (since I'll be needing to lasso-cut into them to make the collage happen)?
 
Basically, what I'm doing right now is creating a canvas, placing two JPG images saved as TIF for testing, selecting "Edit Content" and cutting into them with the lasso, saving and switching back to my canvas. The modification is applied and correct, but when I select "Replace Content" and choose the same test file from its original source place (as I would do when the photog hands me over the retouched image), the relink removes the data I've just created and just inserts the full-sized image, thus destroying my "collage".
 
What am I missing here?