I'm just going to put it out in the open, Avalonia and Atensia have an official unofficial live and let live get along to get along neither of us want a war so let's just not go out of our way to step on each others' toes thing going on arranged via pm (specifically regarding Calzone, but ultimately inclusive of more), that's why Swat can say with reasonable certainty that I won't embroil myself in this mess (also I have another one to deal with on the other side of the world against Asar's ally). Avalonia was involved in Calzone, when it seemed remotely profitable to do so, but not in the end - the New Union was not then prepared to defend itself from what would have followed, having only recently reclaimed the fatherland (HN is big now, too; would be a bloody, painful, devastating war for both sides if we went at it). All that said, the New Union and the HN aren't buddy buddy either - the Cassian faith as a political entity is still something to be kept away from the fatherland (ergo the Calzone truce), although trade with them is currently a noteworthy cog in the plan for world domination a strong nation.
The New Union will take in any refugees should they make it to the New Union, as has been the policy for any governments in exile and refugees for the past several millenia. The New Union will not get involved militarily at this point.
However, a representative is sent to Cassanoia to reason with the Pope &/or the Emperor of Albiton so that those who wish to leave Espovon peacefully for neutral territory during these violent times may do so, perhaps on New Union ships.
The New Union pledges to send 50,000 horse archers, 40,000 light cavalry, and 10,000 heavy cavalry to aid in the conquest of Ytsur, and possibly more troops as needed. Along with these troops will go military observers, engineers, cooks, messengers, morale officers, and strategists. Time will be needed to mobilize these troops and horses for such action, however (particularly if the HN is willing to be reasonable and boats are needed to evacuate refugees from Espovon).