bbp_get_reply_title_fallback( $post_title = '',  $post_id )

	function bbp_get_reply_title_fallback( $post_title = '', $post_id = 0 ) {

		// Bail if title not empty, or post is not a reply
		if ( ! empty( $post_title ) || ! bbp_is_reply( $post_id ) ) {
			return $post_title;
		}

		// Get reply topic title.
		$topic_title = bbp_get_reply_topic_title( $post_id );

		// Get empty reply title fallback.
		$reply_title = sprintf( __( 'Reply To: %s', 'buddyboss' ), $topic_title );

		return apply_filters( 'bbp_get_reply_title_fallback', $reply_title, $post_id, $topic_title );
	}