Colin L
Tour Winner
And there are no rules laid down by the R&A for greensomes and if you ask them for a ruling they wouldn't give you one so basically my point is the committee could come down on any ruling they wish to apply.
While I agree that your won't get a greensomes ruling from the R&A, I don't agree that a committee could, for the situation described, come up with any other ruling than the one I suggested above. As soon as you have selected one of the drives, that is the ball in play in a foursomes format - a recognised format to which all the rules apply.