Multiple input MFT

Hi

I'm trying to create custom MFT with multiple inputs (audio or video) from multiple Media Sources (i.e. webcam capture and video file for example). It works fine with one input from either source, but if i try to switch to two inputs ProcessInput/ProcessOutput methods never called on my MFT. 

So my questions are:

1. Do I need to implement custom Media Session to make this setup work?
2. Do I need to implement custom Topology Loader to make this setup work?