Useful Links that would explain how the flow is split when two or more centrifugal compressros are operating in seris mode

Here are two links related to your topic:


http://www.stealth316.com/2-3s-compflowmaps.htm#fm

http://www.baycontrols.com/pdf/EnergySavingsBroch.pdf

The second zones right in on your specific suject of multiple installations.

All I did was do a serch for " calculate flow centrifugal compressors in series" and brings up several sites , give it a try.

Learning the Internet and how to make it work for you will save you tremendous amounts of time.