Linkable materials within Shader Graph

Hi guys,

How about a making it so you can link in materials that you have already created within the shader graph? I know you can copy and paste, and put into groups etc. But this would allow you to have linked instances of a material (for example a base master material that is used by many others in a mix?)

Appologies if this is already possible. I made a mockup below to illustrate what I mean:

Image