My aunt has a form of dementia, not formally diagnosed. She goes between her boyfriend's home and her sisters. When at her boyfriend's house, she thinks there are two Daves. She insists there are two and you can not tell her otherwise. When she is with her sister, there are times she recognizes her sister and other times she thinks she is her aide. She will sit in the same room and try and telephone her. She gets very frustrated and upset when she can't reach her by phone. Any suggestions for my aunt on how to help her sister recognize her? Or, is this hopeless?