Using an Irule to load balance between multiple pools

Read what you posted and read the article a bit closer:

It is possible to add a local virtual server as a pool member to a BIG-IP standalone or redundant system. However, the BIG-IP does not respond to its own ARP requests for locally hosted virtual server addresses, and thus is unable to establish a network connection to a locally hosted virtual server. As a result, if you add a locally hosted virtual server to a BIG-IP load balancing pool, no traffic will ever be sent to that pool member, as it is not possible for the system to monitor or load balance traffic to that pool member.

But it also states this:

Beginning in BIG-IP 9.4, you can specify a local virtual server as a load balancing target for another virtual server by using the virtual iRule command. To direct traffic to the second virtual server, apply an iRule that uses logic similar to the following example to the first virtual server (the one that will accept client connections):

when HTTP_REQUEST {
   if { [HTTP::uri] contains "param=x" } {
      virtual VS_2
   }
}

/Patrik