My brother in law refinished his kitchen, replacing the plaster ceiling with drywall. Later he removed a wall between the kitchen and dining room/living room. (Those ceilings were still plaster.) Although he did an excellent job mudding the seam it has since cracked several times. He says it will always crack as one is drywall and the other plaster. I was wondering if there is some new product available that has some expansion quality to it that he could use instead of regular joint compound. I know there are paintable caulks available. Also would mesh tape be better here? Thank you.