This is a superb question.

Some CALEX Flow Thru pilots are given two seniority dates. One for date of hire at CAL and the other original hire date for pass privileges, etc. Their date of hire at CAL (Not CALEX) is all that matters for seniority integration.

This brings up other issues. There are many former CALEX pilots who think they are entitled to their CALEX hire date for pilot seniority issues. Some think that if it wasn't for CALEX, CAL would have gone out of business. In fact, F/O Corey Franke submitted a report / demand to CAL management stating that his group of pilots (CALEX) are better qualified, better educated and have better flying skills than established CAL pilots. Because of this, he made demands their pilots are placed into immediate positions of authority (I.E., CPO, Training Dept. etc.). He also advocated policy to get rid of many senior pilots as possible. It is not clear if management has officially gone along with the "Franke Report" but almost all of his demands have been met.

I will refrain from giving my opinion about these things. You make up your own mind.