assume Jason is the father anyway. It's either that or say it was a rando or artificially inseminated. To make it soapy, I could see them going the Jason is the father route.
Way more fallout there. Carly and Jason are BFFs. Look at how she reacted to the fact he didn't tell her Drew played hide the salami with Willow. She will have an absolute meltdown over Jason revisiting history that she orchestrated decades earlier.
Pure motives for Sasha have already left the building by sitting on two secrets. Remember, she was planning on skipping town altogether.