City of Clockwork

So what if Sophie went back in time and told Will and Jem how their story was going to end. How Tessa seemed not to have loved either of them because she continually went back and forth between them. What would they change? How would that affect Clary and Jace? If Clary didn't have Jace, would she have survived the war? (For those who hate Tessa and think Clary is an idiot)