This happened to me ONCE!
I told the parent that I had already confirmed the number of lanes, if they wanted to reserve their own lane next to us??? well here is the number to the bowling alley.
They did, and their kid was BEYOND embarrassed that they did. They were the only parents bowling in that lane. All the others dropped off the kids... it was a 13yo birthday party.
The kid apologized to me for her parents doing that.