When I do the steps outlined, iTunes still asks me whether I want to delete everything that is currently on my iPhone. All I want to do is add a playlist or a song manually, without affecting what is already there in any way. Why can;t this be simple?

When I follow the steps outlined in "Manging content manually on iPhone...", iTunes asks me whether I want want to delete everything that was previously synched. I just want to add a playlist or a song, without changing/losing what is already on my phone. Why can't it be simple?

Note: I have a very large music library on my server so want to be very specific about what goes on my iPhone. It also tells me that the phone is synched to a "previous library". If that's so - how do I find and recognize it?

Thanks