Kudos to the constructor, Patrick Berry! This puzzle is brilliant! And very challenging! So, since I (a) figured out the theme, (b) completed the puzzle, and (c) did so with no errors, I’m feeling quite brilliant myself!
Theme: The puzzle is a rebus. The same two letters occupying one square are repeated four times in each of the theme answers.
22A. Comic strip about the Patterson family = For Better or For Worse
45A. #1 on the American Film Institute’s “Greatest Movie Musicals” list = Singin in the Rain
73A. German-born Emmy winner of 1960s TV – Werner Klemperer
94A. Various things = This that and the other
4D. 1942 Cary Grant comedy = Once Upon a Honeymoon
15D. Elocution phrase = How Now Brown Cow
47D. Initiates a conflict = Casts the first stone
61D. Classic name in crossword puzzles = Margaret Farrar