$attachment = [
  'guid' => wp_upload_dir()[ 'url' ] . '/' . basename( $path ),
  'post_mime_type' => wp_check_filetype( basename( $path ), null )[ 'type' ],
  'post_title' => "$mlsNum $id",
  'post_content' => '',
  'post_status' => 'inherit'
];

$attachmentId = wp_insert_attachment( $attachment, $path, $this->postId );

// Generate attachment metadata and create resized images.
wp_update_attachment_metadata( $attachmentId, wp_generate_attachment_metadata( $attachmentId, $path ));

$gallery = get_post_gallery( $post, false );
var_dump( $gallery );
var_dump( $post );

wp_update_post( array(
    'ID' => $attachment_id,
    'post_parent' => $parent_post_id,
));

$args = array(
    'post_parent' => $parent_post_id,
    'post_type' => 'attachment',
);
$attachments = get_children( $args );