Question about Arlo Ultra 2 VMS5440-200EUS Set of 4

I currently have a VBM 4000 Base with 3 Arlo Pros that I'd like to expand. Since the price of the Ultra 2 camera alone is $300, I'd be better off getting the set of 4 Ultra 2s. Question: As the set includes the base station, is it better to connect the 4 new cameras to my current base or connect my old cameras to the new base (which I can't see the reference to in the set)? Thank you