The Welcome song might be one of the most adorable songs from the second season, so many thanks to Lifeinsteps for writing up sheet music and a midi for it! This pony fan did a brilliant job capturing the charm of the original into a piano arrangement.
Here is the sheet music, and here is the midi file. I suggest playing this song whenever someone new walks into the room.
You can also head over to Lifeinsteps' Youtube channel.