Branching in a vendor branch

[address@hidden]

I have a project in CVS which is a feature enhancement patch to an 
open source project.  My feature enhanced code is checked into the
trunk.  Each major release of the open source project is checked into
the CVS vendor branch.  I have been developing successfully in this
manner for quite some time now.

What has happened that is different that I don't understand how to
handle is the following.  The open source project had to create a security
patch to the last production release.  A branch was created off the last
release tag, and the changes for the security patch were stored in 
that branch.  This is where I am a bit lost.  I don't see a direct
way to create a branch within my vendor branch so I can track this security
patch release.

I do see in the CVS documentation you can have multiple vendor branches,
like the RED and BLUE team examples discussed in 13.6 here:
  https://www.cvshome.org/docs/manual/cvs-1.11.6/cvs_13.html#SEC104

This is not the same as creating a branch within a vendor branch.  However,
I will use this mechanism to track the security patch release in my
situation, unless someone here can describe a better way to accomplish what
I am trying so solve.

Thanks for any suggestions you may have,
Adam