after(existing, targets, options) {
                if (this.get('type') === 'automatic') {
                    return;
                }

                const queryOptions = {
                    query: {
                        where: {}
                    }
                };

                return Promise.all(targets.models.map((target, index) => {
                    queryOptions.query.where[existing.relatedData.otherKey] = target.id;

                    return existing.updatePivot({
                        sort_order: index
                    }, {
                        ...options,
                        ...queryOptions
                    });
                }));
            }
@this {Collection}
@param {*} existing
@param {*} targets
@param {*} options