Filter child records via reference object

I have a master data view (Questionnaire) and data grid (OptionRating) showing multiple records related to the questionnaire. I want to filter option ratings by option. For that, I added a drop box to the grid search area referencing the Option entity. Unfortunately, the Option drop down shows me *all* available options from the entity, instead of only those related to my questionnaire. I tries to alter XPATH for the search field, but I do not know how to reference the questionnaire. How do I solve this problem?
1 answers

Instead of $currentObject try ‘[%CurrentObject%]’
The former is only available in microflows while the latter is available in widgets.