space inside a word

In french language it happens that two words fall onto one syllable (siehe attached picture). That means I have to add space inside the word. When I use the space bar the cursor moves to the next word. Somebody an idea?
Bildschirmfoto 2017-01-05 um 18.57.43.png

You can use Shift + Alt + space for this.

If you type an underscore _ then Dorico will turn it into an ellision slur!

Yes, this is the way to go.