Managing multiple changes and branches

[Matt]

My question is regarding the best way to use CVS to manage different
changes to a project.  Our project has recently reached a maintenance
phase, so we have a few people working on bug fixes and small
enhancements and we have another couple of people working on one major
enhancement.  So everybody needs access to the repository, however we
don't want the major enhancement to affect the maintenance team's
work.  At the same time, it would be nice if the enhancement team
could be up to date with the maintenance team's work.  What we thought
is we would create a branch for the enhancement, and let the
maintenance go along like normal.  The problem with that is that in a
test repository, I could not get the branch to be able to get the
changes from the trunk.  The answer may be to use the branch for the
maintenance work, but in order to not get enhancement code into
regular production builds, we would have to maintain the single branch
until the time when the enhancement is finished and they can be
merged.  The manual seems to warn against using this approach in favor
of just creating new branches.

Our only requirement is that the enhancement code not affect the
maintenance code, yet the enhancement code needs to be up to date with
the maintenance code.  Did I make any sense at all?  How have other
teams approached this scenario?

Any advice is greatly appreciated!

Thank you.

matt.