I’m not a believer in treating kids differently but in this case you’ll likely need to be more restrictive on where your second student goes due to her needs.
There are some schools out there, like Arizona which has large merit and has the SALT Center - which I’m not sure is for your student - but a support service that you might need.
But wherever she ends up, your second student will likely have a more restrictive list of schools she can attend.
So if it were me, when you start looking at schools, budget first and hopefully your first student understands there may need to be restriction in choice to truly inexpensive. This way you’d have a bit more money for the second student.
Wishing you well.