Redefining network settings when creating vApp from template

I need some assistance with redefining Network settings on vApp instantiation.

I want to able able to change the network that is defined in a vApp Template when I deploy a vApp from it. For instance, if a vApp Template had 2 VMs, each with a single NIC directly connected to an Org network; how could I go about removing that Org Network and adding a different Org network to the vApp? Then also be able to change each VM NIC to this newly associated Org Network?