(A2-6)  Here we're looking to combine Lucrezia's speed and Cormorant's speed, each measured relative to Nefertiti, to find their relative speed as Nefertiti sees it. Everything is in the same frame of reference , so it's straightforward. Galileo rules and no relativistic considerations are necessary. 

So Lucrezia's velocity relative to Cormorant, as Nefertiti sees it, is just the difference between Lucrezia’s velocity and Cormorant’s velocity in Nefertiti's reference frame. If we call this relative velocity ΔvN, we have:

         ΔvN  =  wN  -  uN