Need a way to manage lists of recipients

Users of this tool want to have a way to manage and edit re-usable lists of recipients.
Desirable features:
- meta-lists containing other lists
- ad-hoc editing of lists without having to create a new list:
    e.g.: there is a list X of recipients A-F. A user may want to send a resolution to (X except C).
    This should not require creating a new list Y containing A,B,D-F.