Get related items by "Sibling" Relation

macro.php

add_filter( 'jet-engine/listings/macros-list', 'register_get_related_items_by_sibling_relation_macro' );

        function register_get_related_items_by_sibling_relation_macro( $macros_list ) {

                $macros_list['rel_get_items_by_relation'] = array(
                        'label' => 'Related Items By Sibling Relation',
                        'cb'    => '__get_related_items_by_sibling_relation',
                        'args'  =>  array(
					'_rel_id' => array(
						'label'   => __( 'From Relation', 'jet-engine' ),
						'type'    => 'select',
						'options' => function() {
							return jet_engine()->relations->get_relations_for_js( true, __( 'Select...', 'jet-engine' ) );
						},
						'default' => '',
					),
					'_rel_object' => array(
						'label'   => __( 'From Object', 'jet-engine' ),
						'type'    => 'select',
						'options' => array(
							'parent_object' => __( 'Parent Object', 'jet-engine' ),
							'child_object'  => __( 'Child Object', 'jet-engine' ),
						),
						'default' => 'child_object',
					),
					'_rel_id2' => array(
						'label'   => __( 'By Sibling Relation', 'jet-engine' ),
						'type'    => 'select',
						'options' => function() {
							return jet_engine()->relations->get_relations_for_js( true, __( 'Select...', 'jet-engine' ) );
						},
						'default' => '',
					),
					'_rel_object2' => array(
						'label'   => __( 'From Sibling Object', 'jet-engine' ),
						'type'    => 'select',
						'options' => array(
							'parent_object' => __( 'Parent Object', 'jet-engine' ),
							'child_object'  => __( 'Child Object', 'jet-engine' ),
						),
						'default' => 'child_object',
					),
					'_rel_object_from' => array(
						'label'   => __( 'Initial Object ID From', 'jet-engine' ),
						'type'    => 'select',
						'options' => array( jet_engine()->relations->sources, 'get_sources' ),
						'default' => 'current_object',
					),
					'_rel_object_var' => array(
						'label'     => __( 'Variable Name', 'jet-engine' ),
						'type'      => 'text',
						'default'   => '',
						'condition' => array( 'rel_object_from' => array( 'query_var', 'object_var' ) ),
					),
				),
                    );
                
                return $macros_list;

        }

function __get_related_items_by_sibling_relation( $field_value = 0, $args ) {
	
	$args = explode( '|', $args );
	
	$rel_id           = isset( $args[0] ) ? $args[0] : false;
	$rel_object       = isset( $args[1] ) ? $args[1] : 'child_object';
	$rel_id2          = isset( $args[2] ) ? $args[2] : false;
	$rel_object2      = isset( $args[3] ) ? $args[3] : 'child_object';
	$rel_object_from  = isset( $args[4] ) ? $args[4] : 'current_object';
	$rel_object_var   = isset( $args[5] ) ? $args[5] : '';

	if ( ! (int) $rel_id || ! (int) $rel_id2 ) {
		return;
	}

	$relation = jet_engine()->relations->get_active_relations( $rel_id );

	if ( ! $relation ) {
		return;
	}

	$object_id = false;

	if ( $rel_object_from ) {

		$object_id = jet_engine()->relations->sources->get_id_by_source( $rel_object_from, $rel_object_var );

		if ( ! $object_id ) {
			return false;
		}

	}

	$related_ids = array();

	switch ( $rel_object ) {
		case 'parent_object':
			$related_ids = $relation->get_parents( $object_id, 'ids' );
			break;

		default:
			$related_ids = $relation->get_children( $object_id, 'ids' );
			break;
	}

	$related_ids = ! empty( $related_ids ) ? $related_ids : array( PHP_INT_MAX );

	$related = array();
	$relation = jet_engine()->relations->get_active_relations( $rel_id2 );

	switch ( $rel_object2 ) {
		case 'parent_object':
			foreach ( $related_ids as $object_id ) {
				$related = array_merge( $relation->get_parents( $object_id, 'ids' ), $related );
			}
			break;

		default:

			foreach ($related_ids as $object_id) {
				$related = array_merge( $relation->get_children( $object_id, 'ids' ), $related );
			}
			break;
	}

	$related = array_unique( $related );

	return implode( ',', $related );
}