pointer class hierarchy

I decided that today I would do an implementation of a mathematical graph. The graph would be composed of node objects, with each node containing its own data, and pointers to multiple other nodes. To make the class even more useful, the next() function would take an input variable and return only the nodes that are reachable by that variable. For example it would look something like:

Node--(if( variable==key))-->Next Node

This way I could create a NFA subclass. I would need to create my own test_pointer class that would test the path before pointing to the next object. This would be a subclass of pointer. Since the graph would have nodes pointing to multiple other nodes, I would need a multi_pointer class that would point to multiple objects. I would like to know how this sounds and the best way to implement the multi_pointer class. I think that I am going to use std::set because it doesn't have multiple copies of the same value in it.