Hey there, Lela! Thanks so much for popping in to planDisney with this great question.
Your brother does not need to make a separate
reservation for Disneyland Park. When you make a park reservation for a
Park Hopper ticket, you are simply selecting which park you will start your day at. If your brother made a reservation for Disney California Adventure Park, that means he will go to that park first, and after 1:00 p.m. he can hop to Disneyland Park and continue moving back and forth between the two parks as much as he’d like the rest of the day! I love Park Hopper tickets because the parks are so close together. I was there earlier this week and walked from one gate to the other in less than three minutes!
I hope this is helpful, Lela! Also, remind your brother to download the
Disneyland mobile app prior to arrival as it will make it easier to manage his logistics during the day!
Kamini