How to implement Admob mediation in Unity?

Hi,

My app currently has Admob SDK integrated successfully. Now, I want to use it as a mediation platform to serve other networks such as M.Media, InMobi, etc. Can someone explain how can I achieve it in Unity step by step? I have checked the documentation for each ad network and I couldn’t find any specific info about mediation in Unity. Where should I put the adapter? Do I need to include both the SDK and adapter? Or just the adapter is enough? Any help is appreciated, thanks.