For me it makes sense to use delete as default for One2Many as normally records are created instead of linked. For Many2Many the default action is link, so it makes sense to remove (unlink) instead of removing. The proposed API looks good to me.
|2017-11-02 12:44:40||pokoli||set||messageid: <firstname.lastname@example.org>|
|2017-11-02 12:44:40||pokoli||set||recipients: + ced, nblock|
|2017-11-02 12:44:40||pokoli||link||issue4140 messages|