vendor branching and merge

[heatherw]

hi, I use branches exclusively for vendor source. I was going merrily
along with branching and merging till I hit this scenario.
In the interest of time, the vendor sent only those files that were
different from the last set they sent.
Now when I try to merge, cvs schedules all the missing files for
removal. I tried both

cvs co [-rHEAD] -d testdir1 module
cd testdir1
cvs update -j last_import_tag -j this_import_tag

and

cvs co -jrelease_tag (matches head rev) -j this_import_tag

The best thing I can think of doing is checking out the head revision,
copying over the changed files and commiting. Brute force, but anyone
got a better way?
thanks
heather