So we are on the course today playing in a 4 person scramble tournament. We are 20 yds in front of the green and 3 of us chip up on and are close enough for a tap in put. Our 3rd player chips and his ball hits mine and falls in the hole. Is this a birdie chip or are we supposed to re spot the balls and putt?

Tournament uses USGA rules.

The ball that went in is considered holed from that stroke with no penalty provided the shot was from off the green. It is considered 'the rub of the green'. The ball it hit must be placed in the same position as it was prior to being moved.

This is from memory as my rule book is packed away, if anyone wants to correct or elaborate, please do.

Not enough information was given to say if it's a birdie or not, but it is holed out. The ball that was at rest on the green would have to be placed as close to it's original position as possible, with no penalty. You should get that guy on your team again!