Hello , hope this can help you ! , and let me know if there are any other questions
You can try to use a serchable selector , wich you can download here https://marketplace.mendix.com/link/component/116917
then you open the widget it would be something like this
- Then you click on Data Source and after that you can click on selectable objects
- There you can found diferent ways to filter the information the way you want and instead of retrieving the no associated info , for example you can create a new micrflow to do that