I’ve done this in the past and have done it for my upcoming trip as well. When you check in, tell the hostess that you’d like to sit together/near each other and they’ll do their best to accommodate you. Nothing is guaranteed and you may have to wait a bit, but at least you’ll all have reserved seats. Note that your account will not let you make two reservations for the same time, but you can use a second account (I used my mom’s) to make the other reservation for 2.