Since this is getting attached in the `enter_` function I think the following but is possible so you might want to check this.

1. Render the graph with `toggleSeries = true`
2. Add a dataset & corresponding line.
3. Configure `toggleSeries = false`
4. Add a new data set & corresponding line

I would guess that the 1st line would still toggle on/off while the 2nd one won't.