So might Ned try and see Duke Fitzroy married off to Jane or Elizabeth in order to shore up his claims against Mary claiming the throne? Since Mary is likely as not going to have some support (possibly only moral from her family abroad) as being born of a good and valid marriage, whilst Duke Fitzroy's dad was the fruit of an adulterous affair.
Also, would Fitzroy still be under a regency when Edward dies or no? If so, who would be Lord Protector? Dudley? A Howard?
Plus, how might Fitzroy's religious policy look? He'd probably be brought up alongside Edward, but his mother and her family are staunch Catholics (although not above helping themselves to a large monastery or two if it suited them). Plus, would the Kitty Howard affair and the disgrace it caused t o the Howards be extended to Duke Fitzroy?
Even if he remained Catholic, his dynastic enemies would be from the hardline Roman faction in the court. He would have to either get them onside or draw support from the Protestants.