According to Wisconsin law, an absentee ballot requires that it be signed by a witness who also lists his or her address. Should the ballot not contain the a witness address, the ballot is disallowed and must be returned to the voter so that the witness can provide that information.
However, according to a report from the "Dan O'Donnell Show," sources claim that "clerks and vote counters" in the state wrote in the witness signatures themselves. Furthermore, the report claims that the election workers chose to write in the addresses because they were illegally advised to do so by the Wisconsin Elections Commission (WEC).
If the poll workers did in fact write the addresses in, the ballots are invalid.
"The statute is very, very clear," said retired Wisconsin Supreme Court Justice Michael Gableman. "If an absentee ballot does not have a witness address on it, it's not valid. That ballot is not valid."