My husband and I have 3 children, each one year apart. We have our 529 account divided evenly. We based the tuition we can afford on that amount, allowing more for financial aid and any loans the child is willing to take on (we are limiting the loans as well). If you look at the needs of all four of your children, you can either afford ND prices for all or you can’t. If you can, let her go to ND if that is what she wants… If not, then OSU it is.