Hello!
I had a quick look for you, but I think double and triple breakthrough scenarios are very rare. All I can suggest is doing something with some of the D-day Breakthrough boards that have been posted before:
D-Day Landings: Breakthrough Format - Campaigns and Scenarios - Memoir '44 Fans (memoir44fans.com)
From what I understand, there will likely be some difficulties representing the shorelines, but I gather these scenarios can be printed as they are.
As for Overlord, I’m stuck. Sword and Omaha beaches each have an Overlord map, but they are not connected with each other (in fact, they’re at opposite ends of the Normandy beaches).