Managing pairs of files as an individual

I know that Windows Explorer has the ability to manage pairs or groups of files as a single entity, at least with HTML files saved using Internet Explorer.

I'd like it to handle other pairs in a similar manner; specifically, I'd like to hide the "XMP" files that Photoshop saves alongside "CR2" image files (essentially, it contains the metadata for how the Canon Raw image was opened/developed).

Is there a registry tweak that would allow this behaviour, or would I need Canon or Adobe to implement all sorts of COM interface magic?

No. it's a windows feature created by microsoft specifically for ofline website files. it's a hardcoded feature in explorer that checks to see if you are moving a .htm/.html file. If you are explorer will look for a matching folder of the html file name with an extra "_files" and move that folder automatically.

It's nothing special. You can try it yourself. Make a blank "test.htm" file on your desktop. then make a folder named "test_files". drag and drop either the html file or the folder and watch as it moves the other one.