Enlarging a prop hole is a "Good News - Bad News" proposition.

Good news - It's easy. You don't even have to be overly careful, because the drill will naturally follow the existing hole.

Bad News - The drill can "Auger" its way into the hole, so be careful that you are holding the prop securely (and - especially with an MA Prop - make sure to hold it with a glove and/or remove the edge flashing so that IF the prop catches and tries to spin, you won't get sliced up)

If you have access to a drill press, this would be a good time to use it.