if broker supplies you a completed 8949 showing all your activity that is a detail report.
TurboTax doesn't offer any way to e-File a detail report so if you want to use the 8949 supplied to you, you have to file on paper via US Mail.
For 1040X that's no problem since it has to be mailed anyway.
To add the 8949 use the summary option to enter the subtotals on your detail 8949.
Then you will have two 8949s to include with form 1040-X, a summary 8949 and a detail 8949.
Keep a copy of the detail 8949 for your records.
In fact, keep a copy of your submitted amended return for your records.
