Hi Eugene and thank you for your response.
The jpegPhoto property in not vital for me at this time. But in the future it would be used by my company.
The thing is that the jpegPhoto property supports other sizes(i think <100kb) and the thumbnailPhoto supports a recommended <10kb. So I imagine that you could use a bigger picture in the jpegPhoto property.
Where I work all employees have 2 photos taken of them. One(small) where you can just see the shoulders and up. The other(larger) one, you can see the whole person.
So in short. No, don't update the properties together. They should be handled separately.
Maybe this could be incorporated into Adaxes web-interface. You see the usual thumbnailPhoto first and if you click that picture you could see the larger one.
Sure it's best if you dude's read up on this from Microsoft :)