My old high school director had a hard and fast rule regarding
strike... If you did not participate in strike you would
not be cast in the next play.... period... not open to negotation...
And he has never backed down from that rule... it applies to everyone, techies, stagehands, actors/actresses.... everyone
You would need to approach your director about implementing such a policy or another policy better suited to your drama department (should the above measures be too harsh
)