You could consider establishing a “ladder of giving” approach for your children and then grandchildren.

Jim’s grandson A is 18 and his sister B is five. Jim can transfer the five year-old’s account balance to the 18 year-old account balance. In five years when the now 23 year-old A finishes college, Jim will continue to contribute and transfer it back to the younger grandchild B for the time she will use it later.

Ten years later, now Jim has 6 more grandchildren, and all of their accounts will be able to transfer to contribute like a connected web to each others’ degrees, helped by age differences.