gistfile1.txt

add_action( "propertyhive_property_imported_loop_json", 'set_negotiator_from_loop', 10, 3 );
function set_negotiator_from_loop( $post_id, $property, $import_id )
{
    // Negotiator A
    if ( $import_id == 111 ) // change 111 for import ID
    {
        update_post_meta( $post_id, '_negotiator_id', 1 ); // change 1 for WP user ID
    }
    
    // Negotiator B
    if ( $import_id == 222 ) // change 222 for import ID
    {
        update_post_meta( $post_id, '_negotiator_id', 2 ); // change 2 for WP user ID
    }
    
    // Negotiator C
    if ( $import_id == 333 ) // change 333 for import ID
    {
        update_post_meta( $post_id, '_negotiator_id', 3 ); // change 3 for WP user ID
    }
    
    /// and so forth
}