Part of Zodiac was added later?

[Koen G]

Yes, I will do my best to explain it easily . Lisa is a professional palaeographer, which means she specialises in medieval handwriting. She studied the handwriting in the VM and determined that the main text ("Voynichese") was written by five different people. We actually suspected this already, because Prescott Currier said in the 1970's that there were at least two different scribes, but probably more. Lisa confirmed and improved these findings.

She did this by comparing a few typical letters. For example, the first writer always writes n in a certain way. The second writer writes it in a different way, and so on. 

This does not mean that some pages were added later. As I said before, it is well known that the plants (herbal) pages were written by two different people. Maybe they were sitting in the same room and wrote at the same time? We don't know. 

And this is only about the text. We don't know how many people made the images. For now, we have found no good reason to believe that the images were made by more than one person. Of course this is possible, we just don't know yet.