Perhaps you could add a simple check, like "in the event a unionized operating place is closed, unionized employees must be given right of first refusal for any

Perhaps you could add a simple check, like "in the event a unionized operating place is closed, unionized employees must be given right of first refusal for any job openings for a similar place of operation within 10 miles at no less than their original pay or the average pay of a similar role at the new facility, whichever is greater."