Here is how Princess Yuna and Snowdrop helped Vice Principal Luna deliver the mail in Yuna and Vice Principal Luna.
Later that day, They delivering the mail.
Moon Starlight: What a day at Canterlot High.
Princess Yuna: So, What's going to happen?
Vice Principal Luna: First we're going with Greendale Rocket to deliver the mail and then we'll visit the mall.
Princess Yuna: Of course.
Snowdrop: Sounds good to me.
Princess Yuna: Ready, Luna.
Vice Principal Luna: Ready to go on a train ride, Isamu?
Prince Isamu: (laughs)
Yuna and Snowdrop set off to help delivering the mail while Luna played with Isamu.
At the train station, Greendale Rocket was ready to deliver the mail.
Greendale Rocket: Greetings, my friends.
Princess Yuna: Hi, Greendale.
Snowdrop: We're ready to deliver the mail.
Greendale Rocket: Alright then, Let's get to work.
Yuna and Snowdrop brought out the mail needing delivered.
Greendale Rocket: Off we go.
Just then, Casey Jr. passed by them with his passengers from Disneyland.
Casey Jr.: Hello, Friends.
Azul: What're you all up to?
Greendale Rocket: We're delivering the mail.
Princess Yuna: Vice Principal Luna is looking after me, Snowdorp and Isamu while our parents are gone.
Snowdrop: We're having a lot of fun.
Moon Starlight: Indeed we are, Snowdrop.
Greendale Rocket blow her whistle. Her wheels turns sideways. The Fantasyland Engines had a great chat.