Is it possible that I could create two or more groups and give them different access to the same ftp sites? (using vsftpd)

For instance, Group A would have rw to Site 1, 2 and 3 while Group B would have ro access to Site 1 only, Group C would have ro access to Site 2 only and Group D would have ro access to site 3 onle.

It seems to me that this should be possible, even if I have to have one ftp root directory and put the sites into subdirectories of that folder, using group membership and folder permissions to restrict who can go where and do what.