That's very kind of you to want to offer the parents a cabin of their own, but the children can not stay alone in a cabin. There needs to be at least one adult. If you really want to do something special, the Novice Seniors could volunteer to stay with the children.
There are interconnecting cabins and suites. Princess has what they call a "family suite", which is two connecting mini-suites.
There are a lot of possible combinations.
The good news is you have a lot of time to sort it all out. But you do have to have at least one adult in each cabin.