Dual connection wiring on arcade stick

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Hi guys,

I bought a tekken 6 ps3 stick with the dongle missing. I’d like to mod this stick with both a ps4 controller pcb and a DB15 Neo Geo cable.

So question is how should I wire such thing? Do I have to create a switch to make the signal only go to the ps4 pcb or the DB15 cable? Or this switch isn’t necessary, and I can wire both ps4 board and DB15 cable directly on the buttons’ stick?
If I have to create a switch, can you give me insights on how to make it?

Thanks for your help!