Platinums and Diamonds can no longer arrive anytime they want. Same with FTTF. You will have to select an arrival time, and your brother and his wife will have to select their arrival time. P/D passengers can select an arrival time 16 days ahead, but FTTF has to wait till 14 days prior to the cruise. So if you want the same arrival appointment you will have to wait till 14 days prior to coordinate with your brother and his wife. At the terminal boarding is called by group. Suites and wedding parties are first, then Diamond, then Platinum, then FTTF, and then everyone else. Being connected as Cruise Companions will not give your family members access to board with Platinums, but they should be right behind you.