Yes you can go back to the beginning  and add the 1099R's  .Here's how:

• Click on Federal Taxes (Personal  if using Home and Business)
• Click on Wages and Income (Personal Income if using Home and Business)
• Click on I'll choose what I work on
• Scroll down to Retirement Plans and Social Security
• On IRA, 401(k), Pension Plan Withdrawals (1099-R), click the start or update button