Set Quota for both AD and LDAP users?

I have a Isilon cluster joined to AD domain and LDAP domain simultaneously. Now I want use quota feature to give each user 1TB space, each user also joined AD and LDAP simultaneously and established mapping relations between AD user and LDAP user. I want each two related user in AD and LDAP(one in fact) share the 1TB  quota, How can I do it?