To apply additional drywall over a building system that is exhibiting symptomatic failure (cracking) seems like throwing good money after bad. The initial problem is installing a modular building system in a building that was created for an monolithic surface. Your building is created from flexible building components from the foundation to the framing to the sheathing and siding to the plaster and lath interior. As your building moves from season to season the included building systems (plaster and lath) would move with it. Sometimes the plaster would crack creating its own expansion joints. Properly maintained it would last for centuries. Sheetrock on the other hand will hold its structural integrity only within the board itself, not beyond. This results in cracks between the sheets and at the joints and changes in plane.