That's awesome. I remember your Possible Trilogy topic and I sincerely credit it for how highly I now rate GTAIV's story.
How close Chapter 16's Part 1 & 2 are to 'Diamonds Are A Girl's Best Friend' makes me wonder how much or if the saga of Gracie's kidnapping will affect the Ancelottis at that point, seen as they're already going to have a ton of sh*t dumped on them from 'Catch The Wave' and 'Trespass'.
It's just the way the order of missions worked out to be honest. Chapter 16 - Part 1 is tied to Tresspass and Parts 2 and 3 are tied to Liquidize the Assets. I suppose I could probably throw in a little reference to it in one of the coming missions. The Ballad of Gay Tony places DAAGBF and Entourage together so I would probably have to do it in one of the next two missions in order to make it work.. I'll see what I can do haha.