Anyone breaking a strike needs to be blacklisted as an unreliable crewmember and treated as such for the rest of his/ her career.
If during this strike you are called in to cover for striking collegues, only one possibility, and that is to call in sick or to tell bluntly that you are not willing to break industrial action by collegues.
Have some balls for God sake and stop being the typical selfish but oh so afraid pilot. In any other industry, strike action is followed by everyone and management would not even think about replacing a striking crowd by "volunteers" from a different base/factory. They would all refuse.
Any strikebreaker is not worth being part of a crew as a crew needs trust as a first priority.