I ask because the GMS would disqualify you after receiving questbridge, but I’m not sure if this applies to all scholarships.
Ask the scholarship organizations individually.
Not for small amount scholarships. Money for books, living expenses etc.
Aren’t the Questbridge people available to you for such questions? My thoughts are that you need to read the QB pages to see if they addre IIT. Also you need to read the outside scholarship pages. Remember that Questbridge does not give you a scholarship, the college does. So I would link it is like getting any outside scholarship after getting full funding, the outside scholarship will reduce the college aid. But many of the QB colleges will allow the outside aid to be applied to any loan or work/study first. You will not just get to pocket any scholarship, but it will go to your school and you can consider it a contribution. Also you will have those scholarships to list as awards on your resume and it can look impressive.
QB college match scholarships covers cost of attendance so books and living are covered @brendalili