Not that I know of -- and no, definitely not cannon. On the standing issue, though -- I think that once the old count died, if Donna had not become Dono, and had stayed single, her life would have been pretty damned difficult. I think that marriage was the only way that as a woman she could leave the legal control of her male relatives. Given her specific relative, it might or might not have been possible to escape his control by anything short of abandoning everything and leaving the planet, and that has its own down sides.