We did a Grand Gathering in 2005. It was my family of 5, my brother's family of 4, my parents and my husband's parents. All of our rooms were together-DH and I had a room connecting to my in-law's room, and my brother's room connected to my parent's room. All the rooms were right in a row. That was the nicest thing because it was easy to meet up with everyone, and it was easy for the cousins to get to play together. I made all of the ADRS under my name, explaining that we were a large group. I was told that we might not be seated together when I called, and I understood that, but as it turned out, we were all able to sit together at EVERY restaurant, and we were there for 9 days and a sit down meal each day. We did not do any of the other special things that are available when you do a GG, but that was because we're all cheap and didn't want to spend the extra $$.
If you want to be able to be together at your resort, it is my understanding that this is the best way for you to linked to others you might be traveling with.
I just re-read your question and noticed that you wondered if babies count, and I'm not sure. I do remember that my youngest DD was just shy of turning 3, so she technically didn't "count" as a little one on that trip. You could always call and ask about that detail.