Evening all. I am putting right a large ceiling that is boarded out in 9.5 mm pb and nicely skimmed, but with the seemingly obligatory cracks where the boards butt together without noggins. I have easy access above the ceiling, and with a combination of 50 mm wide strips of wood stuck like sh*t over the butt joints, and subsequently screwed into through the ceiling from beneath, I am confident I have sorted the movement between the boards. I now plan to chip off a band of the skim along the cracks wide enough to take a strip of scrim and make good. Is there any reason not to do this with Gyproc Easi-fill and use multi instead?