I seem to remember reading a ruling like this some time ago, but I can no longer find it.
In a 2 player game there is an enemy that is considered to be engaged with each player. It is the player A's turn to declare attacks. Are player B's ranged characters allowed to participate in that attack?
If so, can player B's ranged characters attack the enemy again when it is player B's turn to declare attacks, assuming they've been readied?