I wish I could understand the obsession with cell phones. My STX also does that. It's maddening. Prior to his drug issues hated talking on the phone! It's gross seeing a person neglect their child over a cell phone. Poor little grandson. No wonder he was acting out.
Sorry you had to go through all of that!!! ****{HUGS}}} I agree with the idea of telling the granddaughter. It's not your responsibility to connect them.