Its been ages since I played NWN1+2. I can tell AoO happened automatically but I am not sure if you could have more than one.
In Pathfinder Kingmaker there is a feat that allows you to have more than one AoO per round. (combat relexes). WotR has it too, plus a mystic feat to get more AoO. It makes sense to use this feat: - When standing close to an archer you get an AoO for every shot they make unless they have a feat to avoid this. - Several of your chars have outflank and/or seize the moment. When somebody makes a crit against an enemy, all other chars get an AoO against that enemy. If the AoO is a crit it can lead to a long chain of attacks. Should the enemy still be alive after this, the next char can get a crit with the regular attack, starting a new crit chain.
But DnD 5E has different rules ( I am not an expert, please correct me when I am wrong) - Shooting while being close to an enemy gives disadvantage, not AoO - You have only one reaction and AoO are not the only possible reaction.
Prof. Dr. Dr. Mad S. Tist
World leading expert of artificial stupidity. Because there are too many people who work on artificial intelligence already