Since it's back for now:
http://nwvault.ign.c....Detail&id=2568
To answer your question, yes and no. The characters are created in game like a normal player starting a new character. The module then starts and then the character can be registered with the henchman system. Then the player exits and starts again, making a new character and plays the game. In game that second character can then call up the OHS system and have the first character join her party as a henchman.
It's not quire what you are asking for but if you pull it into your module you could have a special starting area where the player goes when starting a new character that could give them the option to save that character for use as a party member and the repeat as needed. You still have to have a single main PC though. You can't get Baldur's Gate in NWN
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