How do you import a directory structure onto an existing branch?

[BDCutler]

Hello.  Here is what I have:

/foo
     foo.c
     foo.h
     /mynewdir
            data.jan
            data.feb

The directory 'mynewdir' is NOT known to CVS (this is what I wish to import).
foo has a branch called "foo_new_bp".

I wanted to cvs import /mynewdir onto the foo_new_bp branch.  I specified 
'foo_new_bp' as the vendor tag.  It looked like everything worked.

Here is where I have questions:

1.) I do cvs co -r foo_new_bp foo
     I see the mynewdir and its two files.  I make changes to data.jan and 
     commit it.

2.) I do cvs update -A 
     I am now on the main trunk.  'mynewdir' is still there (?!)

3.) I edit the file 'data.jan'.  The change I made and committed on the 
branch is 
     there (!!!????)

I am assuming now that cvs import is NOT the correct way to import a new 
directory into an existing  directory and put it on a specific branch.

What IS the correct way to do this?  Do I need to do 'cvs adds and cvs commit 
to get the directory and its files onto the branch?  

Brian Cutler