Leander Schäfer wrote:

I have one more question. Which minimal objectclass can I add in order to be
able to use "seeAlso"?

Use a decent schema browser to find out. ;-)

Example:
https://demo.web2ldap.de:1760/web2ldap/oid?ldap://ldap.uninett.no/dc=uninett,dc=no

Enter "seealso" in the input field and hit [Search].

Watch out what's listed under "Usable in these object classes".

Of course you should point web2ldap to your own LDAP server to see what's in
your local subschema.

Ciao, Michael.