If they are not allowed then why did they?
Lightbulbs,
This simply isn't a point worth arguing. You are saying those that strike should be the only ones to benefit *if* VS get back around the table and negotiate a better deal. Look at it from VS's point of view - they'd much rather be rewarding the staff that didn't strike, so they are hardly likely to pay staff that tried to damage the airline more than those that didn't.
But, regardless of that, if you have two people of the same seniority and doing the same job, an employer can't pay one more than the other if the *only* reason is union membership. They can pay individual staff more based on responsibility, length of service, training, experience and all number of factors, but they can't discriminate based on things like race, creed, sex or union membership.