[dokuwiki] ldap for authentication, files for groups?

hello
I can successfully authenticate users against our corporate Active
Directory. But the groups each user has configured there are many and have
nothing todo with the intended usage of the wiki. And I have no write access
to the Directory.

Can I use ldap for authentication and the the files backend for groups? I
such a mixture possible?
I wonder whether I could somehow define my own Wiki groups by listing
usernames.

any help is very much appreciated
thanks,
-frank

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