"add user to group" validation

[Héctor Miranda <hmiranda@insys-corp.com.mx>]

Hi all, just a question.

Is it possible in LDAP (OpenLDAP) that the directory (the schema itself or
by any other mean) validates the existence of a user when someone is trying
to add it into a group?? Thereby, disallowing this "add to group" if such
user doesn't exists.

Thanks in advance.

HMP