That is a tougher situation. One major focus in OJS is integrity; it needs to be able to maintain a complete record of submission activity, and if records are maintained by an external database, there is no guarantee, for example, that the user account will stick around. That's why OJS requires a user account that matches the one in LDAP.
Typically the list of editorial users is small, but if you need to bring in a large number of acacounts, you might consider preloading the OJS database with records from your LDAP database. If so, I can provide advice.
Open Journal Systems Team
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