You will get paid for the first trip you should have been awarded at straight rates. The only way you will get paid for additional trips is if they would have been legal had you flown the first trip. If you can show the first trip cancelled and that would have made you legal for an additional trip that would have been awarded after the cancellation you could make a case to be paid for both. Keep in mind that if they used the contractual option to bypass the trip coverage ladder the fact a pilot junior to you got the trip does not mean your pay protected. The most senior pilot who should have been awarded the trip is the only one protected. I was once number 3 in a large category and was passed over for a 30 hour trip. Happily expected to get 30 hours extra pay only to find the number two guy had a GS in and was legal. He did not even realize he was due the pay but did buy me a nice dinner in AMS!