Hi Sabrina!
Thanks for your question! I'm so glad you're finding the panel helpful. Hollywood and Vine is a good dining pick in my opinion, and my family likes it because the buffet offers a delicious variety of foods so even the picky eaters are happy!
I am familiar with the "party may not be seated together" message you refer to. I have seen it a few times, but I personally have never been split up. My understanding is the reservation system takes into account the amount of guests with reservations, the tables and seats, and the maximum allowed guests at any given time in the restaurant. So while there may be seats available at the time of your reservation, they may not all be at the same table as the reservation system understands it, hence the message. However, by getting to your reservation on time (I would get there 15 minutes early) and letting your host(ess) know how many are in your party, you have a good chance of sitting together. You may be told the wait will be a little longer if it is especially busy, perhaps. While the seating arrangement can not be guaranteed 100%, you can rest assured that cast members understand you want to dine together and they will likely put their best effort into accommodating your request. Aside from that, I actually wouldn't worry too much, especially since at Hollywood and Vine, the seating is easy to arrange for parties of various sizes, and the likelihood of being split up is small.
Have a magical vacation!