Help creating a Template Graph

[Ebae]

Hello I am trying to create a graph in a template that uses an item from another template.
I have Template A that applies to all of my hosts and I have Template B that only applies to some. I want Template B to create a graph that shows has values from Template A and Template B on it. I tried duplicating the item from A onto B, but got this error.

• Cannot inherit item with key because an item prototype with the same key already exists.

Is there a way to reference an item from one template into another or a different way to automatically create graphs that use items from multiple templates?

[guille.rodriguez]

I think you need to create a calculated item in HOST A getting item value from HOST B