I am really new to this arduino stuff and now I am at this point that I cant' figure out one of my problems on my own.

I am using this 2.4 tft display shield on a Arduino Uno. It works fine so far as I have coded a little code for it that displays a start button and after tapping that showing random colors. Now I would like to connect a circuit with jumper cables that are used as sensors. When I touch one of the jumper cables the light connected will turn on.

The problem I have now is that, that specific circuit is using an other arduino because my first arduino is already 'full' because that tft shield is taking up all pins.

How can I resolve my problem? Is it possible to Stack arduino's? is it possible to connect those arduino's somehow? Thanks in advance!