I can feel how hard it is to have a loved one with dementia sir, my grandfather also suffered from that and he forgot all about us. He just remembered the people from his childhood until such time that he is like a months old baby asking for milk. It’s painful but with the love that you all have for him, you can all surpass this challenge that your family have. I can see and feel the love that you have for your dad, and we are praying that everything will go well with you and him. I pray that you will be blessed with more patience. God Bless you always sir :)