Could supernumerary teeth be treated with braces?

If: If there's a place for them. Usually supernumerary (extra) teeth don't have a place in the arch and are probably malformed. See an orthodontic specialist for an evaluation of your occlusion and for treatment solutions available.

Usually not: A supernumerary tooth is an extra tooth. Unless your mouth is unusually large, it is doubtful that braces can create enough room to properly accommodate it. Supernumerary teeth are often malformed as well. The usual treatment is to have the supernumerary tooth extracted so that the "normal" teeth can be maintained. Braces may be needed to correct the positions of the "normal" teeth.