CAD — how to add new topological entities to existing model with sharing of exist

3. It is not clearly described in the specification document, how to add new topological entities to existing model with sharing of existing entities.
Let's say we have 2 vertexes already created and we would like to add an edge.
While implementing EntityFactory interface, a developer have to care about this sharing. Otherwise vertexes won't be shared.
And from my point of view we have to speak about that in the document.

see above