relationship-event-to-topic

<?php
add_action( 'mb_relationships_init', 'your_prefix_function_name' );

function your_prefix_function_name() {
    MB_Relationships_API::register( [
        'id'          => 'event-to-topic',
        'delete_data' => false,
        'reciprocal'  => false,
        'from'        => [
            'object_type'  => 'post',
            'post_type'    => 'event',
            'admin_filter' => false,
            'admin_column' => [
                'position' => 'after title',
                'title'    => 'Related Topic(s)',
                'link'     => 'view',
            ],
            'meta_box'     => [
                'title'  => 'Related Topic(s)',
                'closed' => false,
            ],
            'field'        => [
                'name'    => 'Event',
                'add_new' => false,
            ],
        ],
        'to'          => [
            'object_type'  => 'post',
            'post_type'    => 'topic',
            'admin_filter' => false,
            'admin_column' => [
                'position' => 'after title',
                'title'    => 'Event',
                'link'     => 'view',
            ],
            'meta_box'     => [
                'title'    => 'Related Event',
                'context'  => 'normal',
                'priority' => 'high',
                'closed'   => false,
            ],
            'field'        => [
                'name'    => 'Topic',
                'add_new' => false,
            ],
        ],
    ] );
}