Gameduino 2 and Proto Screw Shield

[kame]

Hello, I am in the process of creating an NES type Controller to use with Gameduino 2. Based on the Pin Diagram below there are several pins that are not being used by the Gameduino but are inserted into the Arduino's pin headers. I am guessing this is to provide secure stability when attached to the Arduino or for future use:
So far I have been able to turn an LED on and off with Touch Tags. I currently have the Gameduino connected to the Arduino via male and female cables.


I want to attach the Screw Shield to the Arduino and then attach the Gameduino to the Screw Shield. I then want to attach several buttons to a breadboard which will be attached to the Screw Shield's unused Pins via the screw terminals.

This is the Screw Shield that I have:
www.amazon.com/gp/product/B00ENEXREA?psc=1&redirect=true&ref_=oh_aui_detailpage_o00_s00

I also saw this Screw Shield on Adafruit but I don't have this shield:
www.adafruit.com/products/196

I don't have much experience with shields and so my question is: If I attach the Gameduino to the Screw Shield and then use the unused digital pins will this damage the Gameduino since there will be an unused pin from the Gameduino inserted into the Screw Shield that will now have current flowing through it?

Am I going at this the hard way?
Is there a better way to do this?

My goal is to design and print a case with a 3D printer to eventually create a Gameduino Boy that has a D-Pad and several buttons.

Thanks for your help,

[jamesbowman]

Yes, any of the green "unused" signals are completely unconnected to the Gameduino 2.