Claimant Commitment

I'm Appointee for my son. I see on here messages about the claimant commitment and that Appointees are exempt from having to give the claimant commitment as are the claimants. I always understood that the claimant is exempt but that the Appointee gives the commitment to let the DWP know of changes.

In my son's UC claim form which I filled in as Appointee I filled in the claimant commitment part of the form - so was that wrong of me to do ?

I get more confused by the day.