<p>Erlang support to partition its nodes into groups using the <a href="http://erlang.org/doc/man/global_group.html" rel="nofollow noreferrer">global_group</a> module.
Further, Erlang supports adding nodes on the fly to the node-network. Are these two features usable with each other?<br>
As far as I understand, you have to name every node on startup to use the global groups.</p>

A node is an executing Erlang runtime
  system which has been given a name,
  using the command line flag -name
  (long names) or -sname (short names).
A hidden node is a node started with
  the command line flag -hidden.
  Connections between hidden nodes and
  other nodes are not transitive, they
  must be set up explicitly. Also,
  hidden nodes does not show up in the
  list of nodes returned by nodes().
  Instead, nodes(hidden) or
  nodes(connected) must be used. This
  means, for example, that the hidden
  node will not be added to the set of
  nodes that global is keeping track of.
So in short , yes, you need to give our node a name to be able other nodes to find it.
It feels that you either are asking without trying out or have a very complex question and maybe an example of what you are trying to accomplish could make it possible to give a better answer.