[GAMEPLAY] Gold/Kill Priority with Gangplank's Q, Kalista's Passive, and Spoils Of War item

In a nutshell, Whenever Gangplank has a charge of Spoils of war (Relic shield build), Q's (Parley) a minion in which Kalista has previously attacked with her Soul-Marked (W) passive, what happens is that Kalista's passive appears to take damage priority.

Because Spoils of war is supposed to take priority, when melee attacking, the damage from Spoils of war and Soul-Marked occurs, and spoils of war takes the priority in the kill, giving the attacker the gold. However Gangplank's Parley is supposed to behave like a melee attack, with on-hit like effects. Normally this would allow him to Q minions and have the bonus damage from Parley and Spoils of war, trigger, and give him and his teammate the gold. Supposed to, but for some reason Soul-Marked takes priority and Kalista gets the gold by default and GP gets nothing, only wasted mana. This is a problem because Support GP is awesome and I cant use him with Kalista because of this.