Ethics of Accepting Unneeded Merit Based Scholarships

Congratulations! It's your decision, but I think the most commonly accepted point of view is that it's totally fine to keep the money. One thing you could do with it, or with part of it, is to give back to a need-based scholarship fund or to any other worthy cause.

Also, at least in the US, it is common for universities to solicit donations from alumni, so if you so choose you will have an opportunity to 'pay it forward' after you graduate.

Again, congratulations!

I think it's healthy to ask yourself this question, regardless of the decision you come to. One aspect you may not have considered:

Since your parents have decided to pass on these scholarships directly to you, you will have a huge incentive to maintain a record of academic excellence. (Indeed, studying for classes might be the best-paying job you can find!) Neither your university nor your family would be unhappy if this was the result.

Personally, I'm sorry to say that when I was in college there were many merit-based scholarships that I was too lazy to apply for, even though (for specific personal reasons) I would have been an extremely competitive candidate. The most important consequence of my laziness was that my family, who made great sacrifices to support me to go to college, bore a greater burden than they should have; as an adult I am ashamed of this and I regret it terribly. But another consequence was that when it came time to graduate, I had no practice in applying for anything: I had never written a resume or CV, I did not have many faculty members who could write letters on my behalf, and most fundamentally, I had no idea how to portray myself as a desirable candidate for an internship, a fellowship, or a job. Even though the first consideration may not apply to you, this one very well might.

You can accept the honor without accepting the money. It will not hurt your CV to have a merit-based award or a string of them. However... you probably know some bright students from pinched backgrounds who are trying to keep their grades up while working. If you put the monetary award into your school's need-based scholarship fund, the next winner would be competing with you on a more even footing and your good grades will mean even more.

This is a pretty strenuous standard of morality, but it does feel good afterwards.