Adding more nodes to a Digimesh

I have created a Digimesh of 3 nodes. I am trying to add a fourth node, but it is not receiving anything. How is it possible please?

can i know the configuration of the mesh network for the 4 nodes

My only problem is that I am confused about the addressing. In a digimesh, are the nodes between a source and a destination considered only relay nodes, or can they process data?