There is a new technology preview you can try:
The FABmep Import for Revit MEP is a free technology preview that enables users to import Autodesk Fabrication FABmep models to provide round-tripping capabilities for as-built/record drawing purposes.
FABMEP allows me to import files from Revit into FAB. This plug-in is supposed to allow you to do the opposite. I want in import my FABMEP file into Revit.