I am trying to minimal work on an apartment unit I own and walls are plaster with wallpaper over them. Due to age, some of the plaster is pulling away from the lath underneath. So as not to get into an enormous mess I have attempted suck the plaster back against the lath by using small one inch metal disc (name: ceiling ??). I now want to mud over the areas to blend them back in, at which point I will prime and paint. My question is, what sort of mud would be best...plaster, durabond, pre-mixed drywall compound and will the mud adhere to the old wallpaper enough to great a bond or do I have to take the walls down to the old plaster? Any insight would be appreciated.