The easy solution is use an external attribute on AD to store old login id of OpenDirectory. Because when pydio do the authentication, it translates the login id from an attribute to user’s dN, then bind(dN, password).
Is there a full documentation of the login process? Is the initial ID saved in the database and only that will be used as common ID? If so, doing a mass update of existing ID in SQL could help us to move from OD to AD here?