Help Please... I am trying to manage music and video on my iPhone across multiple Macs. Both Macs are registered to my same account with Apple. I have read that you can put your iPhone in manual mode and drag music and videos from multiple Macs. In fact, Apple has a technical brief with instructions on it. So, on my "master mac" which the iPhone music is tied to, I set the iPhone in manual mode. I can drag songs on it from that computer. But when I plug my iPhone in the office computer, I can't drag songs, the Manual checkbox is not selected, and if I select it, iTunes asks if I want to erase my iPhone and pair it with this library. What am I doing wrong? Thanks so much for your help.