Update iPhone without Syncing

You can update software on any computer, what you don't want to do is sync if this is not the computer the iPhone normally syncs with. You can disable auto-sync when an iPod/iPhone is connected under iTunes>Preferences>Devices.

Now a warning: If anything goes wrong, and I mean anything, you risk losing ALL OF THE DATA ON YOUR SISTER'S PHONE...I mean all as in everything. Your sister needs to be regularly syncing with a computer. The iPhone is not designed as a stand alone device. It is designed to be regularly synced with a computer. If I were in your shoes, I WOULD NOT UPDATE HER PHONE.

The only way to safely do this is to set up her iTunes account on your computer, and transfer all her iTunes purchases to the library under her account BEFORE updating or syncing. (You can have more than one iTunes account on your computer.)

To do this:

1. Disable automatic syncing on connection: iTunes Prefs > Devices > Prevent iPhones...
2. iTunes > Store > Authorize computer with her account.
3. Connect her phone and associate it with her account.
4. Right-click her device tab (left side of iTunes window) and select "Transfer Purchases."
5. Update.

Message was edited by: modular747

Did you read the OP's post carefully?

She has purchased apps and music on her phone so I don't want to backup, restore or associate her phone with my computer.

Yes I did!

Yet the only SAFE way to update her phone remains the way I stated - allowing her to set up her account on his computer.

Also, it's unclear if the OP understands that there can be multiple and separate iTunes accounts and libraries on his computer.

Message was edited by: modular747

You/re welcome.