Complex sentence: This special has an appearance by Pebbles & Bamm-Bamm's twins at the end of the special; however, this special aired three weeks before "Hollyrock-a-Bye Baby", in which the twins were born.
Split into simpler sentences: This special has an appearance by Pebbles & Bamm-Bamm's twins at the end of the special. However, this special aired before Hollyrock-a-Bye Baby where the twins were born.