Django维护模型对象的版本

I have a model Goal which has two M2M fields and is referred to by another model Event. Now, the requirement is such that Goal is editable which means I can add/delete from M2M fields and add/delete events. But editing goes through moderation and only after approval the changes are to be reflected or in case of rejection changes must be reverted.I have a model Goal which has two M2M fields an