VA Retroactive Pay

I am ready to file my 2025 taxes and know that my DFAS 1099-R income does not include the VA retroactive  reduction of income due to an increased disability percentage. I know the amount withheld, but don't know how to report the reduction in my 1099-R income without filing and doing a 1040X after my return is submitted. I want to reduce my income by the VA amount, but can't figure out the right way to do it on the return I'm getting ready to finish and file?