I need help

My FBIL asked me to make him a photo montage for when people are being seated at his church to play on these huge tvs.

He wanted me to have their 'first'dance song playing in the background of this but I told him no way, because no one should hear that until... their first dance.

Soooo with that said...What should I use?

I'm having a hard time with this

FYI: Their wedding is this Monday.. I could kill him for asking this late