Multiples proxy for 1 servername

Hi all,

We do reverse proxy to access from internet to some documentation
filtering by ip address. These documentations are hosted on commercials
For 1 base we are often redirect between 2 or 3 (sometimes 6) servers.
And we have access to more than 50 bases !
Do you know if with nginx it’s possible to do proxy_pass (and
proxy_redirect) to these server one 1 virtual name ?

I want to write something like this

I try it with different location for each server but it’s doesn’t work.

Thanks in advance for your help.