First, Middlebury is not test optional. Second, a 31 would not help at Bowdoin and similar schools given the middle 50% was 30 - 33 with an average of 32.
For a student with a 4.0 gpa unweighted in the top 3.5% of her of class there is no reason to provide data points that are negative outliers when clearly she doesn’t have to. I am not saying a 31 is a bad score but it is a negative outlier compared to the rest of the stats. Submitting the score might give the impression that her GPA and class rank aren’t legitimate. She is the perfect candidate for the upper tier test optional schools.
Family income of 100k+ does not mean you don’t get financial aid. At the more selective schools you are gunning for, income cutoff is different. At Stanford for example, income of 125k still gets you full tuition, full tuition. Don’t make assumptions about financial aid. Your dad or mom should most certainly run the school specific calculators.