As far as the company were concerned LIS was started and always intended as a lower cost base. All the employees and outsiders in the know knew that. Some opted for all sorts of reasons to take the job at LIS in full knowlegde of the situation/contract. Once the positions were filled the company had their wish.
There is no real justification now in demanding equality with other bases. By all means fight like everyone else to improve T&C but don't expect parity with the other countries now. Notwithstanding that both sides have to honour the signed contracts. If the company are breaking any part of the contract I can understand the strike call; if not I cannot see the justification for a strike. The only thing that will improve the T&C now are supply and demand; if there are no pilots willing to take the jobs in LIS as the need arises the offer will improve.