You are allowed to change the primary occupant on a reservation by contacting Recreation.gov by phone. There are some exceptions:

Yosemite & Half Dome
  • The customer name and/or primary occupant may not be changed on any reservation
  • Any request to change either will require a cancellation and new reservation. All fees will apply and you must hang up and call back to attempt to secure a new reservation
  • The primary occupant can only be changed when the reservation is being made, if it differs from the customer making the reservation

Alaska Cabins
  • After the reservation is placed, you can only change the reservation once
  • If you've already made a change and you need to make another, you must cancel and then rebook during a subsequent call