Your D is smart.
You can make a simple spreadsheet showing your annual fixed costs (mortgage, heat, taxes, insurance), then the “optionals” which she is used to. Back out the amount you have available every month for tuition, emergencies, etc. And then a simple table showing your savings/investments/retirement.
It won’t take her long to realize that at the high end of her college planning, she’s either leaving you guys with nothing to live on every month, tapping your retirement savings, or heaping both herself and you with a bunch of debt.
Show her real numbers. It is hard for a teenager to hear “we can’t afford that” when kids around her seem to be doing it effortlessly.
My own kids didn’t really understand this stuff until they got their first paychecks (fortunately, we made them work during HS). In their heads, you multiply your hourly wage by the number of hours you work.
Then the actual check comes. FICA- who is that? The mandatory “fee” taken out of every paycheck for laundering the mandatory uniform (gotta love fast food).
Where did my money go?
She’ll get there. She’ll have great options. But don’t blow her book money for Freshman year applying to so many schools… time to circle the wagons and get realistic about money, objectives, lifestyle, long range planning.