We've never personally done this, but I know that it's doable. We've had tablemates do it on many cruises. If your family is eating at the main seating, you can go and have a drink and/or and appetizer. Just let the serve know you'll be eating at Palo later so they won't worry about ordering an entree or dessert for you.
Main dinner is at 6:00. Palo is open until 9:00 (and I think until 10:00 on sea days), so you can book dinner there for later. You may have to forego the show that night, or you could book Palo for 7:15 or so, if you'd think that's enough time for the kids to eat. You should be able to eat at Palo with a 7:15 reservation and make the 8:30 show, although it is nice to linger in Palo for a long meal.
As I said on another thread on this topic, there's always something else going on that you're going to miss. There really aren't any bad choices, though. Pick something fun and go with it. There's always next time.....