Neil, I am going to take a stab at your question, although I have no first hand knowledge. But, if she legally takes on your name, then she will have to legally get a new passport with her new name on it. Also, he ID needs to be changed. She cant legally go by Mrs Pridgeon, and then try to keep all her old documents to use them when they are handy. Either she has to go all the way, or go the route that Maxx suggested, where, everyone knows her as Mrs Pridgeon, but legally, her name was never changed.