Complex sentence: Allison walked down the aisle to The Vitamin String Quartet's cover of Coldplay's "In My Place", with her bridesmaids walking down to "Yellow" by Coldplay.
Split into simpler sentences: Allison walked down the aisle to the song "In My Place", originally performed by Coldplay and covered by The Vitamin String Quartet. Her bridesmaids walked down to "Yellow" by Coldplay.