Dynablaster DOS game with 4 controllers

Hello together,

i am new on retroarch. Previously playing Dynablaster in DosBox. It has a mode for 4 players, were player 1 and 2 are usually using keyboard and player 3 and 4 using controllers. I want to use 4 controllers, so DosBox is not an option anymore, as it max. recognises 2 controllers.

So i tried Retroarch with DosBoxPure on Windows 10. The controllers (Xbox, Logitech F310) are regocnized well, but how do i make the setup for the game? In the game i only can choose controller by number, but no setup is possible.

Player 2 is walking with controller 1 and fires on controller 2. Player 3 can walk with controller 2.

Any hints for finding the right setup are warmly welcome.