remote spells on sieged province

[alexti]

I was wondering about the mechanics of remote spells on sieged province. In particular, if the nation A sieges the nation B and the third nation C cast a remote spell, who would be affected
- if remote spell is army killer, for example Murdering winter,
- if remote spell is province disaster like locust swarm, who will lose the gold,
- if remote spell is commander attack whose commanders can be targeted

And what will happen, if the caster is A or if the caster is B? Will it be the same as when the caster is a third nation or not?

And how the domes affect the casting? What is nation B mage residing in the sieged fortress casts a spell on the same province, will it be stopped by the domes existing on that province?