Overwriting a sandbox

[Ajmal Chaumun]

Hi,

Suppose there is a sandbox in which the files were retrieved as follows:
>  cvs co -r LAST_GOOD_BUILD module_name

Some files have been modified (+ directories deletd and added too) and tagged BEST_TODAY.

Does anyone know how we can update the sandbox with the BEST_TODAY tag while keeping the files already checked out under previous tag LAST_GOOD_BUILD but that are not tagged BEST_TODAY. Basically, it comes to saying I want to overwrite a few files on top of an existing sandbox.

I have tried with
   > cvs up -r BEST_TODAY module_name
This does not seem to work; in fact, many directories are deleted.

TIA,
/Ajmal.