Is it possible to bake normal maps from several low polymodels down to a single lower poly model?

TheDonquixotic

I have 4  environmental photogrammetry meshes created using Autodesk ReMake. They're all super hi poly. My plan is to arrange them together into a single environment, and generate a single lo poly mesh that I then bake the textures from the hi poly meshes on to using Marmoset. But they're super super hi poly! And I'm not sure I'll be able to compose them together in Blender, or Marmoset. One of them is 18 million polys alone. 

I could lower their poly count automatically when I export them from ReMake, and generate normal maps, but I worry that doing in doing so I won't be able to then transfer the detail in the normal maps down to the meshed together lo poly version that I plan on making. Is marmoset able to take a  lo poly mesh in the hi poly section of the baker, with a normal map applied and then bake that normal map down to an even lower poly mesh?

Any advice? Is there a way to do this in zBrush that I'm unaware of? I've got zBrush, Marmoset, and Blender. 

EarthQuake

That is not currently possible but it something we will likely add in the future. If you have a good enough GPU you may be able to simply load your highpoly into Toolbag though - on my GXT 980 I've tested scenes with up to 50 million triangles.