There are many fine comedy dramas out there. One of my favorites is Love Actually. Then there's Knifes Out, The Noel Diaries, Scrooged, and of course, Miracle on 34th Street. Many of the best dramas use comedy as relief from tension. It serve a very useful purpose by allowing the audience to break from the dark and heavy content. It can be a breath of fresh air and if it advances the plot, even better.
Many Cary Grant movies effectively used comedy with drama for example, Arsenic and Old Lace, The Bishops Wife, His Girl Friday, Charade, To Catch a Thief, The Take of the Town, etc....
