Apologies if this has been answered, I couldn't find this information.

I'm making a mileage run internationally, ORD-FRA-IAD, on a LH ticket. I'm going to use UA miles for the domestic DEN-ORD and IAD-DEN legs.

If I end up misconnecting from LH to UA at IAD on the return (I'll purchase a cheap SW ticket for a flight the next morning as insurance), would I rather have the IAD-DEN award ticket be on a separate ticket from the DEN-ORD leg in terms of getting the 12,500 miles back?

Thanks