You could try making an account at each credit bureau and see if they will allow you to add that information. Making an account is free but they will try and upsell you on various services so be cautious in what you agree to.
This source of income may never end up in your credit file but it would be information you can give a lender if you apply for new credit in the future.
Your credit report doesn't affect your tax returns. If this income is non-taxable, it's non-taxable.