How to Best Use Lumen RT for Staging works

I am looking for the best Methodolgy for reusing LumenRT Terrain with different Staging DGN models of Civil/Construction Work.

I have tried copying both LumenRT and DGN files and giving the same name, but the copied LumenRT file will not display the copied DGN file. It seems to recognise different layers from the renamed DGN, but the Geometry will not display. I am hoping to find the best way to create different stages of the construction sequence from Ustn and be able to leverage the same terrain and detail created in Lumen RT. Any help appreciated.