My daughter has bought her first house and has been busy decorating it, unfortunately she has a problem with a couple of ceilings, she tells me she has given them two coats of Dulux Vinyl Matt and a yellow tinge keeps showing through, i have a feeling the people who she bought the house of were heavy smokers, and its the nicotene showing through, unfortunately she lives a couple of hundred miles from me and i cannot get there to help at present. If she were to repaint the ceiling with an oil based undercoat,to stop the stains showing through , could she then repaint it with the Dulux. If i had seen it before we could have washed it all with a bleach solution, but its to late for that now. Any advice appreciated.