score:8
Most airlines belong to one of the three big alliances, in Alitalia's case Skyteam, but Etihad does not. However, since Etihad is a large investor in Alitalia, they encourage flights with them by accepting their flights for mileage in the Etihad program.
That's it, really. Or in simpler terms, Alitalia is friends with investor Etihad and fellow Skyteam member Aeroflot, but Aeroflot and Etihad don't know each other.