CHC has a 'right of appeal' with the Canadian Federal Court of Appeal. This is the avenue they are presently pursuing. If they fail in this attempt, they can appeal to the Supreme Court of Canada where they do not have 'right of appeal'. The Supreme Court must determine if the case is worth hearing and ruling on. They may very well decide not to hear the case. To the best of my knowledge, that is the end of the appeal process.
A previous post suggested striking as a possible work action should CHC continue to drag their heels. I would not like to consider that option until absolutely no other avenue is left open to us. We are a union, we have union rights. CHC has their right of appeal and it would appear they will use it.