Maybe you can start with the following template?
You have to check that all answer sheet are exactly the same! (eg. if shuffled, all questions should have the same number of choices)

Thanks for sharing the template, I'll give it a try. I noticed the subject codes are in binary format. Is it possible to use a code grid instead, where students can bubble in A, B, C, D, etc., and A corresponds to 001, B to 002, and so on? It may sound fancy, but we have a large class of around 1500 students using this AMC, and we want to minimize errors. If students only have to bubble in one box for the subject variant code instead of multiple in binary format, the error rate would be much lower.

For example, a sample OMR sheet that I used this semester is attached. So, I want to modify `\AMCIDBoxesAO` so that instead `binarycode`, a code grid should appear with A,B,C,D, and so on. We can assume that there will be almost 26 subject variants.