It was revealed as a result of your investigation that Francis' now elderly daughter had poisoned Johann and was taken away in handcuffs by the authorities. She'd felt guilty after Francis' luck and health had declined after Johann's death, and had been the one playing the sonatas as a sort of tribute to his memory. Of course she won't be doing that any more now that she's in jail, probably on death row, thanks to you. Talk about your depressing endings...

Francis' wife left him when he revealed that he had a daughter by someone else, she ruined him and he and his daughter lived together until his death. He taught her to play and she was the ghost that you hear playing the moonlight sonata which he had played for her as a child... or something like that, either way it was a happier ending.

It was Johann who told his daughter about Francis' daughter in the ending I got -- while on his deathbed. It was not Francis who told her. So there's another difference.