Force/Lock Lightmap Assignment (solved)

I have a tiled background in a scrolling environment. I want the group of assets in the background to be duplicated while retaining the lightmap that is baked on them. Is this still possible?

Moving the group of assets in the scene automatically removes the lightmap associated with them. Can I lock the lightmap they are associated with, or manually assign the lightmaps back to them?

Thank you in advance!

It seems the workflow for this process is outlined here: