Have you tried creating a group with objectClass let's say "group" and
use it as an OU for the child entries?

Let's say you make an OU "MyGroup" of class "group" and then use it as
OU when adding users.

Build the distinguished name like this:
cn=user1, ou=MyGroup, c=country, dc=domain, dc=com
where MyGroup is of objectClass "group" and is previously added to the
AD with distinguished name: cn=MyGroup, c=contry etc

Take a look at http://ldaptemplate.sourceforge.net/quickstart.pdf and
see what ldaptemplate can do for you to ease your work.