Withholding tax for legacy payments

Hi All,

We are going live in 2 months (middle of the year) and migrating data from legacy system to SAP. All AP open items are paid in legacy system only and no AP data is migrated into SAP.

IRS doesn't allow companies to submit two different 1099 forms for each vendor (one from the old system, and one from the SAP.

We have around 600 withholding tax vendors and payments are made in legacy system. How to bring the historical withholding tax data for standard 1099-MISC report S_P00_07000134? And print/submit a single form for each vendor?

Thanks,

Anusha