My 1099-int shows interest received from US treasuries in box 3 as well as interest income in box 1. I need to adjust the interest in Box 3 for accrued interest I paid. To simplify, I was told to split the 1099 into 2 separate 1099's one for interest income in box 1 only and the other for the US treasury interest and make the adjustment on it. Is that legal to alter the original 1099? Thanks