Quest Functions

Ok, this is a question for GMs, or anyone who knows how the quest system works. As of right now, I'm working on a line of quests (shameless link). I have a scenario, and I need to know if I can make it work.
Basically,
I have an item, and I want to split the quest 2 different ways, depending on whether you have the item or not. Kind of like this:
NPC (1/1): Do you have [This]? If not, you must do --- and bring me [That].
And I want two different things happening depending on what you bring him.
Is this possible?

 

Bump
Pls help

 

PLS I HAVE HANGRY SUPPORTERS TO FEED

 

I'm pretty sure that's possible, yes.

 

Yes that is possible using Command Blocks. It is done in a few quests already.

 

Ok, thanks for the feedback!