Well, here's how I have it wired
P360 (Up) --> T-Stick (Up, connected on NO) --> I-PAC
P360 (Down) --> T-Stick (Down, connected on NO) --> I-PAC
P360 (Left) --> T-Stick (Left, connected on NO) --> I-PAC
P360 (Right) --> T-Stick (Right, connected on NO) --> I-PAC
The P360's ground is connected to the Opti-Pac. The T-Stick Plus's ground is daisy-chained to all the other ground's (which is connected to the I-PAC).
When everything is connceted like this, the P360 won't respond what-so-ever. The T-Stick Plus seems to work but everything is reversed (the up direction registers a down keystroke).... very strange.
If I unplug the NO connections on the T-Stick Plus then the P360 works perfectly.
You said I should have them wired in parallel... Can you explain that a bit more?
As a side note, I have some buttons wired the same way. For example, the player 1 button 1 is shared between a couple of buttons. I simply have them daisy-chained from one button to the next on the NO connector.