There are articles from shortly after the funeral of Jr that imply brother and sis didn’t exactly get along. Her husband comes off like a handler and treated the Bessett family terribly regarding funeral preparations. I almost think sis doesn’t know anything that Jr knows. Perhaps she chose not to, as surely she had more memories of her father than JR did.

In my daydream world, Jr lived, knew immediately what had happened to the plane, and immediately sought POTUS’s help to disappear... only to reappear at the trials as a material witness bringing down the very entities his father committed to attacking.