I had to call to cancel our preferred seating for a March luau (changed arrival to July) and asked when they would release July (to book as soon as possible for the best seating). The lady informed me that preferred seating is assigned in advance and is at random. It is not based on when you booked (contrary to my previous belief) or when you arrive (like they do general seating). So, I would wait for your friend and book together OR call and have the reservations linked after booking (if they do that; I have to assume they do). There has to be a way for them to know when parties who booked separately are wanting to be seated together for when they do their assignments. If you want to be 100% sure, you could call and ask. My entire call to cancel took less than 5 minutes.