Lots of kids' clothes. Kids' toys. Kids' books. Kids' medical kit.
Clothes that span multiple seasons or climatic zones: warm, cold, heavy rain, snow. Extra shoes. Especially when you know that your things will get wet and that you will have only occasional opportunities to dry them.
Suit/dress/fancy shoes if going to a wedding or other formal event.
Bulky gifts.
Bulky sports equipment.
Lots of kids' clothes. Kids' toys. Kids' books. Kids' medical kit.
Clothes that span multiple seasons or climatic zones: warm, cold, heavy rain, snow. Extra shoes. Especially when you know that your things will get wet and that you will have only occasional opportunities to dry them.
Suit/dress/fancy shoes if going to a wedding or other formal event.
Add that, and 80L is not much volume...