Please see my message above. I responded to yours and have further questions. Your help is much appreciated in responding to my questions. What may take an electrician who can eyeball the situation a few minutes to handle has to be done the hard way over the internet to avoid electrocution and your house burning down. There are too many wiring variations to give a generic answer and you already have an uncommon situation with a shared neutral and a single receptacle next to a duplex receptacle.