I don't even see how there could be an argument over retro pay.
Our amendable date to JCBA DOS = a certain amount of money that should have been paid over that time for distribution based on changes in hourly rates for CAL pilots
Your amendable date to JCBA DOS = a certain amount of money that should have been paid over that time for distribution based on changes in hourly rates for UAL pilots
To make each side whole as of DOS is going to require different dollar amounts for each pilot group, with the majority going to L-UAL pilots. That should be a given and has been pretty much accepted here since your rates are lower than ours. Every line pilot I know is aware that L-UAL pilots are going to see the biggest % pay increase compared to us in the new JCBA so logically your retro will be higher.
Now if you are talking a "signing bonus" pool of money that management wants to give the pilots, that is a completely different story. There could be a philosophical fight over that unless there is an agreement to proportion it like retro pay. However, no one I know will entertain a "signing bonus" and we have indicated as such to our reps, MEC and the negotiating committee. We all expect to be made whole come JCBA and a "signing bonus" won't cut it for the majority of us.