Related Clues:

• 'Oh, and another thing,' on a ltr
• Ltr.'s second afterthought
• Second afterthought letters
• Letters that further extend letters
• Second addendum to a letter ... and a hint to 18-, 34-, 44- and 62-across
• Here's even more: Abbr
• Afterthought to an afterthought, for short
• Letter writer's addendum