Two recommended features

In the types of graphs I am creating, links can be 'explanations' they link a hypothesis to a conclusion. The arrowhead is at the conclusion node. Some of the links though should be bidirectional (arrowheads in both directions, for instance if two hypotheses contradict each other). I don't see a way to do that with your API

Also, some explanations link more than one hypothesis to evidence. For instance
hypothesis 1 might be - Living creatures have a high rate of population increase
hypothesis 2 might be - Food for living creatures has a low rate of increase
Conclusion might be - Living things are in a struggle for existence against each other.
In that case, it might be nice to have a big circle appear around the two nodes that work together to arrive at the conclusion, so if A and B together result in C, then A and B could be in an ellipse that contains both nodes.
Thanks.

Start by reviewing the graph API entry point and the existing graph layout and viewing behavior. Define how bidirectional links and multi-node explanatory groups should be represented and rendered, then verify that both requested feature cases work without disrupting existing graphs.