Sounds like you want HA-JNDI affinity -- i.e. once a user connects to JNDI on a particular node in the cluster, he always uses that node. If none of your EJBs on the node are clustered, when you download an EJB proxy from JNDI, the proxy will always talk back to the server it came from.
Something you can try -- in the all/dpeloy/cluster-service.xml file, HA-JNDI mbean you find this:
Try changing it to:
With that, once a client VM accesses a particular node via HA-JNDI, all further access from the VM will use that same node, unless the node fails.
BIG CAVEAT: I've never tried this, never heard of anyone trying it, and have thought about it for about 10 minutes. Use caution, test well, don't be surprised if there are issues, etc etc.
Note that this architecture doesn't sound HA at all.