Combining Two Itunes Accounts?

Yes this is totally possible, iTunes is kind enough to allow multiple iTunes accounts to be associated with a specific iTunes library. It is not so much combining the two accounts but letting iTunes know it is okay for music to be played from both accounts on that computer.

Once you have all the music from the two music libraries imported onto the new mac, you will need to play one of the protected aac music files from each of the iTunes accounts you have. iTunes ask for your password for the respective account you bought the music from and then it will authorize that computer with your that iTunes account. From there you will be able to listen to any of the music on that computer whether it is from your library or your wifes.

Why not just always manually sync. Thats how I have mine, because I put music on my niece and nephew's ipod and I don't think I want a whole library of Jonas Brother in my ipod, I also don't want to put Richard Cheese on their ipods either. I just pick and drop the ones that I want.

What if you created a playlist and just keep adding the songs that you want into there then you can select all and drop and drag to your ipod.

There's an iPod preference in iTunes that allows you to only sync checked music. Just uncheck your wife's music before you sync and then check them again when you're done. She can do the same with your stuff.