Longevity is not given more weight per say via the ALPA merger policy. It is one of the the three items required to be considered in designing an SLI. In the past several mergers longevity has been used with different weights. Most of them have used around a 15% weight. Which was the VX side proposal. The AS side proposed a 70% weight I believe.

The proposals are very long and would be impossible to post here. But to give you the gist of them...

Alaska says that VX pilots received a huge windfall by getting to become Alaska pilots and adopting their contrat. That they have massive advantage in longevity and that should be primary. Except for their first officers which should get special feathering above VX first officers despite lower longevity.

Virgin side says that although weight should be allowed for longevity a more consistent hybrid model should be used set of past precedents. That carry through the whole list.

Both sides put in captain seat protections.

The proposals create a pretty diverse results depending on where you are on the list. There is no point in predicting because depending on the decision you could see a very different outcome.

Everyone is going to be irritated about the final list. So honestly this discussion is pointless.