I'm not sure what you are seeing as advice, you can't issue a 1099-INT because you aren't a bank.
Your brother's tax return simply reports all the interest as "interest not on a 1099-INT". There is a way to do this in Turbotax.
Your situation is a bit more complicated. Before e-filing, the IRS would have said to not include the interest on your return, and to attach a copy of the 1099 and a letter of explanation when you mail your return. The letter would include your explanation, and give your brother's name and address, so the IRS could verify he reported the interest. With e-filing, that is less easy to do. Turbotax does not allow for the attachment of statements or documents. Tax professionals can do this, so one option is to see a tax pro and have them file for you and attach the documents suggested. If you want to use Turbotax and e-file, there are two options.
1. Leave the 1099-INT off your return. Be prepared for the IRS to send a letter (this is automated) about the missing income, you would reply with your explanation.
2. Add the 1099-INT, then also add an item of "other" or miscellaneous income in a negative amount to offset the income, and for the reason, write something like "Interest reported in my name but belonging to my brother Robert Smith". This gets the 1099 on the return so it satisfies the computer matching, but the IRS may still send a letter asking for an explanation of the offset.
