How to pre-populate MB relationship field from URL for add new post

Hi have "tramp" and "tramp-contact" custom post types with a MB relationship (Relationship ID: tramp-contact-to-tramp). On the front end I need to provide a link for editors/admins to click to add a new tramp contact and would like to pre-populate the related tramp in the "Add New Tramp Contact" admin screen using a tramp_id URL parameter.

I'm already doing this with other Metabox custom fields without an issue, but I'm unsure how to target the MB relationship field so that it is pre-populated in the Add New Tramp Contact screen.

I'd like to do something like the code below, but unsure what id the relationship field has.

function preload_tramp_relationship_from_url_on_create_new_contact() {
    global $pagenow;

    // Check if the current page is the "add new post" page for the "tramp-contact" custom post type
    if ($pagenow === 'post-new.php' && isset($_GET['post_type']) && $_GET['post_type'] === 'tramp-contact') {

			/* see https://docs.metabox.io/filters/rwmb-field-meta/ */
 	
            add_filter( 'rwmb_tramp-contact-to-tramp_field_meta', function ( $value, $field, $saved ) 
        {
            $value = isset( $_GET['tramp_id'] ) ? $_GET['tramp_id'] : $value;
			
            return array($value, $field);
            }, 10, 3);

        }
}
add_action('admin_init', 'preload_tramp_relationship_from_url_on_create_new_contact');

I've tried both variations:

rwmb_{$field_type}_field_meta: apply to fields with a specific type
rwmb_{$field_id}_field_meta: apply to a field with a specific id

Screenshot of Add New Tramp Contact page with the relationship field I want to pre-populate:

https://share.zight.com/4guWyGXK