I think rose is the second daughter of Prince and she is Sarahs younger sister... and the lady in the previous chapter who was in the hospital could be their mother...
ITS JUST A GUESS
Damien is misinformed I guess, I don't think do Kevin wouldhave killed Damien's fiancee. I know Kevin is also have bad sides but he won't do this ever. How did Damien got to know that Kevin has did this?