I believe the Crown had CN explain her method of note making. And everything would have been entered as an exhibit.
The Crown wanted CN as a witness to get the notes in as evidence against Millard. The Crown would not want to attack her in examination-in-chief. What good would it do for their case against Millard? CN is not on trial here. As for the Defence, they can ask leading questions hoping to get an answer that will somehow help their client. Dungey IMHO is simply suggesting that DM and CN were supporting each other and pointing the blame towards MS together, as a "couple". But who knows what CN wrote back to DM (except maybe DM's mother), there's simply no evidence other than CN's testimony. So I can't see Dungey making much of this that will benefit MS's defence. Again, only in my humble opinion, all Dungey can really do is play down CN's testimony about MS drinking, not working, needing to grow up as she put it I believe, etc. He has to be careful questioning her because he never knows what she's going to answer. He may want her to say MS really didn't drink that much, not like hard liquor, just a couple of cold ones....she may answer, are you kidding me!! He was given a nickname for his drinking....juice....DM called him that from time to time.