How do I make multiple things in the background the "ground and have them as "shadow catchers" I am building a scene with multiple planes in the background because I want to have the multiple planes working as shadow catchers except, when I put them in the background, they don't behave as shadow catchers because blender renders them out (in the background composite node) and, I don't have a texture on any one of them. How do I make them behave as such? Only the original &quot;Ground&quot; plane behaves that way.
You have different options.
Do activate shadow catcher in EACH of the object properties like this in CYCLES:

If you're on EEVEE, setup the shadow catcher MATERIAL to assign to all the objects you want to catch the shadow on, like this:

Alternatively, you can use holdouts to separate what you need but (trimming) the pixels to later compose. Activate the HOLDOUT option in the filter selection, and activate it at COLLECTION level for all your grouped (collection) elements.