multiple hardware interfaces on a single joint

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Hi!

I'm trying to implement a controller that can switch between torque control and position control based on user's needs. It seems to me that I need to assign multiple hardware interfaces to every single joint in urdf and spawn both position controller and effort controller during launch. But is that even allowed?

I also skimmed through the ros_controllers repository on github and it seems I can also use feedforward controller to achieve what I mentioned above. But I can't find any documentations or even questions posts related to that controller. For the controller, can I pass more than one command in the controller? And can I change the type of command during operation?