Shammer, welcome to the forum!
There are several programs that will probably do what you want.
I'd suggest trying the freeware version of MASH (Microsoft Agent Scripting Helper) available at:
http://www.abhisoft.net/mass/You can also get the MASS software there as well (Microsoft Agent Scripting Software). It will let you view all the possible animations for each respective agent character.
There's also Cyberbuddy's Story Builder program that allows you to create a script for each agant character complete with screen location, sounds, changing character identities, vocalizations and even singing! You would simply not enter a character's name and it would not show (as you mentioned).
There's a lot more on Agentland.com and other sites like Botspot.com.
Hal could do a lot of this for you but as mentioned, it would be difficult to keep the kids from chatting with the program.
Hope this helps!