I don't think a solution to automatically merge layers will be possible.
A quick thing you could do to filter things is us a layer extension and sort this to the bottom of the list. You will still have a lot of layers, but the other office their layers should be out of your way.
You could maybe with a clever combination of 'by name' and 'by index' replacing of layers in attribute manager get to some sort of automatic solution, but you would still need the same amount of layers.
I would try to match up their layer to your layers by index. For example let's say you have a layer called 'walls' with index 20, look for something similar in their file and get their layer name to go to index 20. After this you can just merge your template on top of their file and replace the names.
You would be having a few PLN files to be used with loading in the modules and replacing attributes after you are done and saving a new module from this file.
Personally I'd load their modules in a new emtpy file setup the way I like add the extension and call it done.
I'd also have a seperate file for the combined work, to keep my own files tidy.
Maybe sharing PMK files of the finished plans is a cleaner solution. Just stitch those together on layout?
Erwin Edel, Project Lead, Leloup Architecten
www.leloup.nlArchiCAD 9-26NED FULL
Windows 10 Pro
Adobe Design Premium CS5