Hi @David_Fernandez,
You can relate entities to each other by using the relationship custom field type. The Linking Entities Together unit goes more in-depth on the relationship types available and how to set it up in the Knowledge Graph.
For these relationships to be searchable within an Answers experience, you will need to go to the backend configuration and add the custom relationship field (that you created) as a searchable field within the products vertical.
Let me know if this helps!