There is a bug in LDAP JNDI prohibiting the addition of attributes to a class when that class is the parent of another class.
Example:
class "C1" with some attributes
class "C2" with parent "C1" with some attributes
class "C3" with parent "C2" with some attributes
Failing operation: adding attribute "new_attr" to "C1"

Trying this operation results in LDAP JNDI generating a "MOD DELETE" then a "MOD ADD" operation on "C1" only. The "MOD DELETE" fails as the "C1" object has children, hence this operation would break the schema.

According to the Directory Server dev. team., the "MOD DELETE" operation should be performed on all the children recursively in reverse order, then on the targeted class, then the "MOD ADD" operation should be performed on the targeted class, then recursively on the children classes, as shown below:

1. MOD DELETE on "C3"
2. MOD DELETE on "C2"
3. MOD DELETE on "C1"
4. MOD ADD on "C1"
5. MOD ADD on "C2"
6. MOD ADD on "C3"