We also have second seating (yay!) and there are 8 people in our part (2 families), 4 children in our party, Boy- 12 yrs, girl - 10 yrs, daughter -10 yrs and daughter - 8 yrs. Perhaps your 11 year old boy could hook up with our 12 year old, and your 8 year old girl could hook up with my 8 year old...
This will be our 1st 7-day cruise, but we have done 2 3-days and loved them!!