Is there coving up? If not, and you can make out bulges/cracks then leave paper and overboard. If there's coving and is staying, then overboard is tricky. Paper off, screw and scrim joints, pva, pregrit and skim or unifinish if not too dry. I tell customer that re-screwing of joists and tape gives 50/50 chance of no cracks again.I then tell them to use crack-free ceilings paint (polycell) if they do re-appear. All this goes in writing on the quote as they're some idiots out there thinking your plastering can defy the laws of physics and joist movement.