Ember hasMany relationship save on create

I'm trying to create an ember data record with a hasMany relationship from a POJO, and it's been remarkably difficult. This is using ember-concurrency (hence the task and yield syntax.

  saveEntry: task(function* (obj){
      let entry = yield this.model.get('entries').createRecord({
        groupId: obj.objectID,
        name: obj.name,
        ...

      }).save();
      obj.owner_ids.forEach((user_id) => {
        this.store.findRecord('user', user_id).then((user) => {
          entry.get('owners').pushObject(user);
          entry.save();
        });
      })
   }).drop();

So the tough bits are the 'obj.owner_ids', which is an array of user_ids. I add each to the array, but then need to save after every pushObject or it doesn't work. And even when it does work, it is throwing a bunch of network errors (probably due to race conditions on the save). There must be a better way, but I haven't found it.