If your son attends a college that meets full need for all, you very well could get some need based aid when your daughter is in college at the same time.
The net price calculators really are set up for incoming freshmen, but you could plug your 2018 income and current assets into your son’s college net price calculator and indicate 2 in college. This would only be an estimate. But maybe worth trying.
You indicate you are full pay for kid one…so your family contribution calculation was at least the cost of attendance. If your EFC is very high, than even with two in college, it could still be near or above the cost of attendance.
And lastly, remember that the net price calculators are not particularly accurate if you are divorced, self employed, own a business, own real estate in addition to your primary residence.
I think it’s fine to call the financial aid department and ask…at your son’s school.
@twoinanddone the FAFSA doesn’t ask the cost of other kids’ colleges, but some Profile colleges DO ask this question.