Spanair doesn't operate FRA-MAD-LPA - they have 3 FRA-MAD flights per day feeding onto all other JK MAD departures throughout the JK system. The LPA flight only has an LH codeshare because Spanair is a Star Alliance member. It is more than possible that German nationals were onboard but there are a lot of direct FRA-LPA flights in summer so I dont think it would be a large number.