Hi Phil,
Thanks so much for the straightforward input. It works quite well!
However, the part I suppose I'm not following exactly is how to get the batch to use the 2nd .xmp for the 2nd jpeg, 3rd xmp. :: 3rd jpg, etc...
As it stands now, the metadata (rating, keywords) from, let's call it, image_001.xmp is being embedded into image_001.jpg. Perfect! However since image_001.xmp is the sole .XMP file being called on by the command, only its metadata is being copied into ALL the jpegs. I'm hoping to have image_001.xmp metadata copy into image_001.jpg, but then
image_002.xmp metadata copy into image_002.jpg
image_003.xmp metadata copy into image_003.jpg
image_004.xmp metadata copy into image_004.jpg
...somehow I'm missing how to get this critical same-name alignment scenario to sync up and ripple throughout all the files properly.
For simplicity I'm using the simplest possible catalogs for experimenting. But I'll attach a screenshot showing my file structure. Pointing the command to the root of the folder, to "find" the JPEGs was simple enough. But by dropping a single .XMP file into the xmp slot in the terminal command, I'm marrying
only it's metadata into ALL resulting jpegs. I'm sure I'm missing something simple.
Thanks again for your patience with a newbie!

—Kevin