Originally Posted by Meraude
Would Edward have been able to marry Jane Grey, or did the church consider them too closely related? If Edward had married Jane and made her his co-ruler (and heir) before his death, would that have made her more acceptable as queen in her own right instead of Mary?
Before the Church of England was established, Edward would have needed Papal dispensation because he and Jane were too closely related otherwise. It was quite a common practice in those times. However, with ties to Rome severed, he would have only needed a blessing from the Archbishop of Canterbury, if that (after all, Edward was the head of the Church of England).
In regards to making Jane his co-ruler, he simply couldn't have done that. Such a change in the line of succession would have required an Act of Parliament. Even Henry VIII, who basically changed his heir(s) every other day, always did it though parliamentary acts (Acts of Succession). That includes the line of succession he established right before his death: Edward and his heirs -> Mary and her heirs -> Elizabeth and her heirs - > descendants of Mary, Queen of France (Henry's younger sister).
If, however, Edward actually went ahead and made the Parliament acknowledge Jane as his legitimate heiress, then yes, Jane would have very strong claims and probably the support of the army. This said, Mary still had the support of ordinary people, so more likely than not, she would still become the Queen. The only difference would have been the timing and/or a possible civil war.