Revit workflow question

I finally got a complex Revit model to export to datasmith and in to Unreal. What I seem to have is one material called ‘Revit Master’ and instances of that material for every different material in Revit.

I guess what I probably want to do is be swapping these out for their own materials (assuming having one master and a load of instances is not good practice). Anyway, because of the way the project is built, there are more than one material element on pretty much every static mesh.

So my question is, is there a way to automate, or at least speed up the workflow of swapping out newly created materials to the material elements within actors?

For instance, all my walls have an exterior and an interior face, the outside needs to be brick and the inside plasterboard / paint. At the moment I can see the two material instances on the Revit Master material in both element slots (aligning with how they’ve been set up in Revit.

This is a full working architectural model, with 2744 actors (I only imported what I absolutely needed, actually slightly less) so swapping out materials to all those meshes or elements is not practical. I can’t just edit the existing material to look how I want as they are all instances of the Revit Master material.

Ok, sorted out the above with ‘Replace References’ command.

Next question is that I have imported a large working model from Revit, and a lot of the lightmap UVs don’t seem to be unwrapped properly. Is my only option going via 3DSMax in order to unwrap those objects ‘manually’ or are there further options to develop the unwrap within Unreal?