It might depend on the ship. I know on the Magic, when we had 8 they put us into the separate room because they didn't have tables for 8. For brunch, they split us into two tables placed beside each other.
On the Wonder, Palo also has a private room for parties of 6 or more that can seat up to 12 if they really cram people in there. If you're booking for 8, might be worthwhile to ask about he private room.
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