You should send out Amended or Corrected 1096 Annual Transmittal letter including not only all the previous 1099-Misc already reported to the IRS but also include the 1099-Misc that was missing. I would write in red the word "Amended 1096" at the top of Form 1096 and then include all the 1099-Misc that are to be submitted to the IRS.
There is no need to be concerned as this is fairly normal and the IRS will accept an corrected 1096 Annual Transmittal Letter.