In general while still not supporting the boozer npc...
NPC Code:
if (playerenters) {
message initial;
sleep 2; //
message ; // only needing sleep if you want to clear the message
}
if (playerchats&&strequals(#c,yes)) {
message newmessage;
}
if (playerchats&&strequals(#c,newreply)) {
message another new message;
}
Sleep is unneeded unless you want the message to leave after a couple seconds, in which case you need to set it to blank