Yarrick reactive shoot interaction with Stormlord Mount Up!

Thought of something funny that my friends are skeptical is legal. Yarrick's ability allows for a 12" reactive shoot at the "end of the opponent's movement phase", and the Stormlord's Mount Up! ability allows for an embark into the Stormlord at the "end of the opponent's movement phase". Can I choose the order in which these happen since they happen at the same time: reactive shoot then embark?