I'm presuming FIFA's ruling as to the ownership of the player [sorry, I know that sounds crass] at the time of the accident is crucial to any insurance claim. Nantes will have insured him, and I'm certain City would have put insurance in place to come into effect when he became a City player. The rights and wrongs of Sala's doomed flight are not going to affect any insurance claim - neither Nantes nor City were negligent.