Paul McCartney does duet with 10-year-old fan during concert

So, what's the back story on how it was arranged??
Her mom spent two months wages for tickets for her and her daughter to see Paul.
Determined to get their money's worth, they talked their way through the many layers of security to the stage where She borrowed Brian Ray's bass for the number. The thing hung down past the little girls knees.
Looks completely off the cuff to me.
Great memory for the girl & her mom.
 
Her mom spent two months wages for tickets for her and her daughter to see Paul.
Determined to get their money's worth, they talked their way through the many layers of security to the stage where She borrowed Brian Ray's bass for the number. The thing hung down past the little girls knees.
Looks completely off the cuff to me.
Great memory for the girl & her mom.

This happened here in Buenos Aires. It was all over the news, but I've heard nothing about how it was arranged, so I'm gonna trust you on that.
And the tickets were pricey indeed.