Donna. Sam. "When All Is Said And Done." It's Meryl Streep and Pierce Brosnan, and the results are exactly what you'd expect from actors of that caliber.
The fact that not a single one of the guys would've been a bad father. They all clearly care about her despite only having just met her, and when they all (separately) work out that they may be her father, all three promise to give her away at her wedding. One gets the distinct sense that, had they known they were possibly her father when she was a child, all three would've gladly stepped up to the plate to be there for her. This bit during Voulez-Vouz is especially sweet (even if Sophie begins to freak out a bit).
Harry: Oh, my God — I've got it! Talk about slow on the uptake! I'm your dad! Sophie: Harry... Harry: No, the penny's dropped now — good and proper — that's why you sent me the invitation. You want your old dad here to walk you down the aisle. Well, I won't let you down! I'll be there!