how do I find unauthorized songs in my library? (previously shared from ex)

Previously in my iTunes library I had a number of songs that were shared between my ex-wife and I.

While I understand and have successfully de-authorized all songs from my library that were purchased through my account (and then reauthorized those tracks on my "purchased" list) I still run across songs from time to time that had been purchased through my ex-wife's account.

I've been replacing/repurchasing effected songs as I encounter them but I was hoping to find a more efficient way of finding all of the songs all at one time. This has really become an issue as I loaded up my library to my newest iPod. It gave me a notice of 88 songs that were unauthorized and unfortunately the list window won't expand to make for an easier time of picking out the songs I want to repurchase (I was hoping to as a worst case solution take a screenshot of an expanded window and then look through things as I then navigate the iTunes store to make my new purches).

Any assist or advice that anyone could float my way regarding this problem would be greatly appreciated. I did a search but perhaps I've not landed on the right search wording as all I got were results that pertained to users having issues with songs that had suddenly lost their authorization info but had been purchased by that user prior.

Much thanks in advance.

Charles