In our house we have two iPhones and an iPad. Each one has a separate iTunes account so we could have different versions of the games instead of sharing. We've upgraded our computer from a PC to a Mac and when trying to sync any of the iPhones or iPad, we get an error message that says that the particular item is synced to a different account. How do I sync the iPhones and iPad to the new computer without erasing all the information on the item?