Is it necessary that all cluster-related packages be from the same Update of RHEL in a High Availability cluster?

Issue

• I need to update a cluster-related package to a later release, but I don't want to update all packages. Does Red Hat support running packages from different releases of RHEL?
• Can I use cman from one release and rgmanager from another?
• Do all RPM packages in the cluster have to come from the same update level?
• Can I run a cluster with cluster-packages from one update and the rest of the OS from an older release, since we've certified our application to run on that older release?