As I don't read or write music it's a bit difficult to explain in words ,but there are many "part" chords (normal tuning) - but it's not complicated.
I play in D with a Capo on the 2nd , Vin plays in G , Leadfingers obviously likes to play in C - possibly - to suit the voice range.
When I say "part" chords ( perhaps they're full chords I don't know ) try this for an example - play A7 , and with the finger which holding the E string (1st string) - stretch that finger to cover the first 2 strings. So alternate between both positions and you have the part which goes:- (with 2 fingers) "Once we'd " (with one finger) "found a key"....(with 2 fingers)"Oh what a " (with one finger) "harmony" etc etc.
Wish I could write music, or better still sit down and show you - even a couple of sketches would help you !!.
Never mind - have fun with the song - and don't forget THAT - no matter how you play it HAVE FUN WITH IT !!!