Welcome to the Disney Parks Moms Panel, Janet!
Thank you so much for sending us your vacation planning question. We are here to help with all the magical details.
As long as you are the "lead guest" making the reservations on the 180 day mark of your
Advanced Dining Reservation booking window, you'll be able to make reservations for all of you. In fact, you could make a dining reservation and include as many people as you'd like, even if they weren't guests of Walt Disney World® Resort.
When making reservations, you'll be able to select the party size with the final step being to select anyone in your "Friends and Family" list to include in the reservation. Your brother should then be able to see the reservations on his My Disney Experience Account as well.
I hope this is helpful, Janet! Please let us know if you having any additional questions as you continue planning.
I hope you can't wait to Be Our Guest!
Faith