I was thinking about what is the maximum number of queens that can occur on the board after only legal moves. The theoretical upper bound would be 18, the original 2 queens plus all promoted pawns. However to have the pawns get past each other they would have to capture the opponents pieces but they could not capture the opponents king or queen, so thats 2 less for each side (although a capture on one side would open for the other - so gets a bit tricker than that I realize). However if so that would be 14, but with that many queens it would be easy to put the opponents king in check or checkmate I guess.
But is it possible to get 14 queens on the board in a legal game and if not what is the maximum ?