D17 is very likely moving to 5 year MChem program at St. Andrews after she gets her year 2 marks this summer. She needs to average a 15 in her second year Chem courses, should be fine.
D20 is applying to some UK schools but could very well end up in US. This means that her freshman and sophomore year will be D17's year 4 and 5 in the MChem program.
So when I fill out the FAFSA for D20 do I have 2 undergrad students or one for each of those years?
Note this makes a 30K difference per year in FA at some colleges for D20. We get nothing with one kid in undergrad college, 30K with 2.
UK considers MChem to be an undergrad program.