That was exactly the type of information I was looking for. That was tremendously helpful.
I should have been clearer from my first message.
The flight starts at 6am in SF and has me arriving at noon in Paris. (with a 4.5 huor layover in DUS)
I then get myself to Madrid and work my way to BCN. Then my ticket gets me to AMS via frankfurt for a three day stopover before going back to Frankfurt and then on to SFO.

So in addition to the first trip, im getting a stopover in AMS.

But those flights are cheap anyhow! If only I could get a direct sfo-cdg and ams-sfo, that would be ideal. Im trying to learn how to use expertflyer to setup alerts for those flights on United.