After you file

Yes, you can log in to your account

You should see amend your tax return in the center of the screen

You will also find this under Previous Taxes

The program will then walk you through everything to amend your tax return to include the K-1.

For more information, follow these links:

What to Include with Amended Tax Returns 

How to Amend 

Tips to Amend 

IRS on 1040X