user/file permission issues...

[bruce]

hi..

i have a file in a dir...

the file was created as root.

the permissions/owner/group have been modified to user 'foo' by root..
chown foo dog.txt
chgrp foo dog.txt
chmod 777 dog.txt

however, when user 'your_foo' tries to delete/cp the file, the sys gives a
permission error.

user 'your_foo' is a secondary member of the 'foo' group.

basically, i'm trying to figure out a way to allow members/users of two
different groups to be able to delete/modify files in a given dir tree...

thanks

-bruce