I didn't fully understand your question, but I Can explain how it works it Qewig. In Qewig, everything is an ovs. If you have a link between two nodes, an ovs, will be created and the links for the nodes will be attached. To connect more than two nodes to the same network, you create a "network" (which is just an OVS) and then attach the interfaces you want. For external connectivity, you would add a "network" and then add one of the physical interfaces from the handler in to that network (ovs).
Not sure if that answers your question, but if not, you can provide a more detailed example and I'll try to explain more.