using head revision in branch after add on branch

[C. Wienberg]

Hello,
I have posted this problem before, but the proposed solutions didn't
work.

Setting: We are using CVS to store 4 projects, that use some common
files.
Common files are in the head branch, every Project has its own branch.

Problem: Some files have been added on a project-specific branch, but 
turned out to be of common interest, so we want to move them from the 
branch to the head revision. "Move" means, CVS knows that there is no 
special version of the file on the branch, and will deliver the head 
version, if checkout with the "-f"-option is done for any branch.

What we tried: 
* Delete the version from the branch, add on head revision:
CVS remembers, that the branch version is dead, and does not deliver
the file at all on "checkout -f -r <branchname>"
* add in head revision (additionally), merge branch version to head
version: "checkout -f -r <branchname>" after the merge will still
deliver
a branch-specific version of the file. Changes in the head version are 
not reflected in the branch, we still have two redundant versions.

If we kill the ,v-File from the repository, andd add the file on the
head branch, we will loose the file's history. Is there any better way?
All we want is to get the symbolic name <branchname> point to the same
version as head!

Kind Regards,
Christoph