With electronic cheating, one would just add Biden votes by machine and then add paper ballots without valid signatures.
Maybe in one or two localities (like Philly for instance, or Atlanta). But not system wide like what has been accused. Again, go to the premise of this discussion, we are talking about a County in Georgia that was deep Red for Trump. The "conspiracy" is supposed to be systemic. So these ballots that are added to reconcile the inflated machine counts would have to be done in 152 counties without getting caught.
Also, I think there are easy safeguards to prevent that in any decent system. I won't make the case since everyone assumes Dominion was intentionally stealing the election.
Unless they don't manufacture ballots for flipped votes in red counties.
For example Antrim County MI, didn't the machine and the paper ballots not match?