I posted both the updates side by side to show the difference in these stages, even though the lighting does not do it justice. The paper is actually a creamy white and even though I took the photos under a daylight bulb I still can't seem to get an accurate photo of the colors. It is best to go outside and take the photo in the shade on a cloudy or sunny day...but today is raining so I am not risking it! As there are many more layers to go before I need to worry about displaying accurate colors I am not going to worry about it.
Despite the photo quality, I hope you can see how the paint appears much softer and there is more of a translucency or opalescence to the grisaille which when the flesh colors are built up, still shows through giving a more natural skin effect. That being said, I also love the underpainting stage so much that I have left many paintings at this stage as I just really liked the effect.
I think her portrait is coming along quite nicely and there are just minor adjustments needed to capture her likeness more which will be resolved once I begin modeling her form more with the flesh colors. The flesh colors are where things really start to take shape and the ghostly portrait becomes more of a three dimensional solid portrait.