How do I create a parallax effect when my viewport/camera doesn't move?

In my platformer, I have the player staying in the center of the viewport and you move the level around him/her, essentially making the character move to the end of the level by panning the level itself.

My "level" is a bunch of platform sprites pinned to a large invisible object that you can drag back and forth.

Since the camera/viewport is fixed on the player that never moves horizontally, the built-in parallax for backgrounds doesn't work (as the layout is not technically moving).

I have a tiled background on another layer and I'd like to make it scroll along with the "level" object being dragged, but obviously at a slower rate to simulate the parallax effect.

What might be the simplest way to accomplish this effect? (I'm still super new at this!)

Thanks!

Try this:

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That worked perfectly! Thanks so much.