Hi and welcome to the forum I have some experiance with hobby cats and some bigger ones but if you could get a 56' new I would look into a MANTA
42 it's a little bit smaller but it could be sailed by your girls if they can read. It was designed for single
handed sailing and is ready for a circumnav. I requested a price
for one and they sell in sailaway condition for 530k US. They are worth a look.