This parent has already played you/counselors once. For me that eliminates any need for flexibility on my part.
As others have said, you are putting every student in the best position to be successful. A kid that can't play on the level of the group they are in loses their self esteem, and is resented by other students. My only offer would be to play a group below. Sell it that they are being put in a position to be the top of their section, and a leader in the group. I regularly point out that the first chair kids in my second band (or third band) the next year don't move to the bottom of the next band up - they move into the top half of their section. They tend to grow more sitting at the top of the second/third band section than they do sitting in the bottom of the top/second band.
One other possibility - if and only if the kid is a good kid. Make the schedule change, but they don't play in that group. They practice the second band music during class and go to second band sectionals, etc. to play with that group.
All that said, I had one of these a number of years back. On the marching field my assistant had singled out a freshman trumpet player for his great effort. He was also the worst trumpet player in the program by far. When we moved to concert band, he was in the third band. Mom and kid were furious. Apparently he thought because he was pointed out as working hard that he was going to be in the top band. They fought, kid was ticked, so I recorded the first 'down the line test' we had. Just a quick two scales one octave. I played the recording of the whole section (no names) and asked the mom which one she thought her kid was. She wouldn't acknowledge that he was the one that sounded like he was giving birth to his trumpet, but I could see she knew. Didn't hear any more from her (at least on that).