My elderly dad has an iPhone 3 that has never been updated. I use my desktop to update my iPhone 5 and my phone is up to date. Can I use my desktop mac to update his iPhone 3, since it cannot be updated wirelessly? If so, will it screw up my desktop and in turn, screw up syncing my iPhone 5 in the future? He has no iTunes library, no music, no photos, and only a few apps so I'm not worried about losing that on his phone. OR would the Apple store do it? Sorry to be so ignorant! I appreciate any thoughts.