Hello!
How to make Halfnote duols over a whole 9/8 bar?
Hälsningar
Micke
Hi Micke, and welcome to the forum!
Half notes (without dots) are not very useful in 9/8 meter in general. If what you want is two equal notes in a 9/8 bar, I think that is much better represented without a tuplet: 
It is possible to create an 8:9 tuplet of eighths and fill it with two half notes (and there is a workaround to make it display 2 instead of 8), but I wouldn’t recommend that as notation.
Thank you very much Mark!
It´s much better your way, even if it´s fast and the feeling is in ONE and not THREE.
Hälsningar
Micke