odd error Parenting and QGraphicsScene coordinate transforms

[GrantH]

I am writing a graphical node-edge editor, and am implementing hyperedges - single edges but with more than two ends. These are drawn between nodes, as can be seen in the image below, of 2 starting nodes and one ending node.

The following has 2 ending nodes:

The objects and code for creating these is nearly identical, with only the commands and lists for which end changing between the two. The 2-starts version can be dragged around perfectly, but the 2-ends version does this, with the end positions being updated 'twice' - by the same code that works for the 2-starts version.

If I add another 'end' to the working one, it starts giving the error too.

This looks like a scenePos vs pos issue, but it only occurs when the parent edge is split on an outgoing edge, not an incoming one. Could a transform of some sort help?

I have checked the calls for both moves, and they are identical. The structure of the data connecting the items is correct - I have carefully checked it, and again, it works for 2-starts.

Any ideas where to look would be welcomed!
Grant