Establish comunication from the nodes of a pool to the LAN

You can create another virtual server that listens on the VLAN of the BC's, is a 0.0.0.0/0 destination, and has a pool member of the upstream router from the F5. This will essentially make the BIG-IP act as a router for your BC's back into your network.

I would probably do some more intelligent load balancing with your BC's as well instead of having a destination port of 0. You've probably done this to simplify configuration to allow for multiple protocols to be load balanced, but you are missing out on intelligent features like CARP as an example.