JOINING WALL LAYERS

ADDING A LINING TO AN EXISTING WALL and enabling hosted windows and doors to cut the new lining layer

Typically adding say a gypsum plasterboard layer on metal firrings to an existing wall - create a new wall type for the MF lining (plasteboard layer + a metal stud layer). 

Draw alongside the existing wall and align to it including over window and door openings

Join Geometry between the two layers - doors and windows will now cut the new layer