Two in college Fall 2016-->One in college 2017--->Two in college in 2018 assumption ?

As title of thread indicates, year 2017 when we go back to 1 in college is where I have questions. School has said to use NPC calculator, however,NPC calculator was not accurate for 2016. The difference from the NPC calculator grant/scholarship was 27K–>they gave us 33,300. Year 2017 is it safe to assume,(all things being equal from year to year,(income/deductions/taxes), the NPC calculation the school offers to adjust based on the FA package. In other words the 6300 difference in NPC is not going to change?
I realize our EFC changes, its the difference the NPC gave us versus what the school offered is what I am questioning.

School states it adjusts for high cost of living areas/higher than ave property taxes, is this the geographical difference/high cost area the $6,300?
I called the school and asked these questions a week ago, someone was to get back to me, and Im still waiting.

It is year 2017 when we only have one in college that I am trying to prepare our finances/make choices.