But I was able to get past the problem using the trick that @NJres figured out (thanks!). Just to repeat it for anyone who finds this thread in the future:
When asked if your child was an undergraduate student, click "yes", and "continue". Put in $0 for the tuition amount, and some random name for the college, then click "continue". Do this for all your children.
Now you will be on a screen listing all your children and their status, with an "X" in the column for "undergraduate". For each child, click the "edit" button, and that will take you back to the screen asking if they were an undergraduate student. This time, click "no", and continue through to the end.
