Form 1099-DIV contains no Box 6c. 

Assuming what you're asking about is payments in lieu of dividends, I believe the appropriate presentation is Schedule 1 Line 8 (Other income, what used to be Line 21), not subject to SE tax, subject to NIIT. You get the same tax answer with fewer Lacerte entries by calling it non-qualified dividends.

Reading the instructions for 1065 K-1 will help answer your question.  Unless your client is a foreign partner and is subject to §871(m), which deals with derivatives that help avoid the higher 30% withholding for residents of non-treaty countries, this is not relevant and not entered anywhere.

@mike188 Which form are you looking at with this line 6c?