Synching iPhone to two iTunes accounts
I have two iTunes accounts. One contains all my music for my iPod and is on our home computer. The other is on my company laptop. I have synced my iPhone 4 to the account on the laptop (so it syncs my Outlook info for business). I want to move the music from the iTunes account on my home computer into my iPhone. But if I try to manually move the music to my iPhone, it tells me that the phone can be synched to only one iTunes library and asks if I want to erase the iPhone and synch with this (my home computer's) iTunes library. How can I get the music from the one iTunes account either into my iPhone or into the other iTunes account? If I elect to "erase this iPhone" and synch with the iTunes library on my home computer, what exactly is erased from the iPhone? Just whatever music I might have in the phone (I have none)? Or does it erase everything in the phone (i.e. apps, etc.). Thanks so much to anybody who can help.
iMac, iOS 4