Yep, you'll have to use the same Apple ID especially if you want iBooks synced across devices. I haven't seen much of a reason to have a separate ID from wife regarding app store (which ibooks is part of in settings). In fact, it would seem to be more of a problem than a benefit.
You can however just log out, log in her ID (settings, app store), download what you need (ibooks, apps, etc), then log back in as you. At least you can for apps. Haven't tried this with books but don't see why it wouldn't work.
12-11-2013 07:28 AM