You can reference into graph as classic object. Geometry port is under "op" group port. To import use ctrl+drag from object manager into graph, that will create a copy of geometry in the graph itself.
You may find some example for iteration in the capsule file pit thread. If the link works, it will get you there + to a comment where more links to resources are mentioned. Great place for better understanding of Capsules + Scene Nodes. 🙂
Use as child Connect object and put all geometry objects there.
Or use objects links input (drag objects in OM which you want use into objects links panel), decompose it and transform geometry with iterations of geometries and matrices to clone onto points node.
But I think first solution is more understand-able 🙂
I share this resource xpresso to generate corrugated cables and sheaths (for electrical systems) that can be extended at will.
As soon as I have time I will make a python plugin