1 - rerun your new 50 lineups on FC, download the CSV file and open it.
2 - go on draftkings, go to lineups, click on the edit entries tab. Pick the slant you want to change, download that CSV file, and open it.
3 - use Excel to sort the CSV file from draftkings. I usually change the color of the lineups I want to change using Excel (use a method like that to know which are the cash games you want to keep the same and which are the lineups you want to change).
4 - Copy and paste the new lineups you downloaded from FC over the ones that you want to change on the DK CSV file. Save and upload it back on the line from the same page that you downloaded the draftkings CSV file.