Not relevant to this thread, but I’m betting MM and David will not both remember at the same time. It is looking like David’s memories are coming back around first, and it will cause all sorts of turmoil if he goes to MM and tries to explain it to her. She is already mad at him.
Not much different than the scene between Charming and Snow in Heart of Darkness, though. If he remembers he’ll just have to show here who she is and kiss and that’s it for her remembering. And yes, I know Emma is the key and bla bla bla, but in that scenario it could just be like this.