I second that.
Guys, let´s not complicate things. There are only five official ranks within a crime family:

- Boss
- Underboss
- Consigliere
- Captain
- Soldier

(Technically speaking, every made member of a family is a soldier, even the underboss etc.)

If a guy relays messages between two parties, he might be called a "messegero", but this is NOT a rank within a family. Neither is acting boss, street boss, acting streetboss, capo´s capo, sidewalk soldier or whatever else pops up in Mafia related articles on Wikipedia.
Ivy´s posts in this thread are right on the money!