Frequently asked questions about Apple ID - http://support.apple.com/kb/HE37
Items purchased on one account remain permanently linked to that account. While in physical proximity it is not difficult to share items using Home Sharing and to authorize her devices to your account but if she moves out of the area this will be impractical.
We can provide more suggestions when you have specific tasks that you want to undertake.
Thank you for your help. So I guess the long term solution is 'start again' and repurchase her content via her new account. Her current Apple ID on her MacBook is the same as mine, so do I just go ahead and change it? What effect will that have on her files etc? Will the content on her (my) iTunes library disappear?I really appreciate your help. Thanks.
Discussions on using purchases from multiple AppleIDs in one iTunes library - https://discussions.apple.com/message/19543804
As I mentioned earlier, the main time when this becomes an issue is if you need to do something involving associating a computer with a particular AppleID. Careful management of your collection should minimize this situation.
iTunes Store: Associating a device or computer to your Apple ID - http://support.apple.com/kb/HT4627 - In connection with, "When you turn on iTunes Match or Automatic Downloads, or when you download past purchases on an iOS device or computer, that device or computer becomes associated with your Apple ID." "Your Apple ID can have up to 10 devices and computers (combined) associated with it. Each computer must also be authorized using the same Apple ID. Once a device or computer is associated with your Apple ID, you cannot associate that device or computer with another Apple ID for 90 days." - Additionally instructions for "Removing an associated device or computer from an Apple ID"
So the first account is really "yours" and you are setting her up with her own account? It helps to know this because if both are "hers" then there isn't an issue with her having full access to both accounts. If in 10 years she moves 2000 miles away and she is pretty much independent then you may not want her to have full access to your AppleID just so she can authorize a device.
Hi, thanks for this. To answer your question - Yes, it is my account and I now want to set one up for her to use independantly on her Mac & iPhone. For some reason (I think speed and eagerness of her to start playing!), when I bought her her MacBook, I set it all up in my name. Same Apple ID etc. I now have the overbearing threat of endless sulking if she loses access to several series of Doctor Who and hours of music by people I've never heard of, yet keep appearing in my iTunes shuffle mix! Thank you for helping me!