Quote TiaB: Sharon wasn't even involved with the Newman's when she had Cassie so why would Ian connect her with them? ~)
That's the question, why would Ian care about Sharon and her baby. She wasn't connected to the Newmans until years later.
We watched Cassie's long drawn out death and have had to endure the endless remembrances of her birthday and anniversary of her death. She wasn't that important in the scheme of things to have her death faked. Nothing would surprise me, but I hope they wouldn't go there. If they have to keep CG then make her a sister or twin, whatever.