Okay so I'll be honest. I skimmed through that special chapter there...and I lost interest halfway through. Many of the icons there distracted me and lost track of the interactions.
So yeah, personally I can't help you where to go from there as far as ideas go. Before writing chapters, I would personally do an outline of the actions and events so that you at least have an idea how to finish the chapter. Hopefully someone else can help!
Agreeing with Bay regarding the general idea of an outline. If you have one in progress I would volunteer to give it a look, it is easier to see in an outline than in the intended draft / product the potential ways the story can go.
As a general idea I would suggest for the outline starting in Sandwich Mode™: start with what would you like the beginning and end of the story to be like, and then work inwards checking the various events you have so far so that you can see what the characters have to change so that you can get to the ending. The idea that the characters have to change something is one of the main drivers to go from an outline to a draft. What you have so far is a good motivation (going for a birthday present) and a number of drivers (characters that give ri and ni stuff to do), next to check is what changes when these things are resolved.