Invalid path selected for Constrained by property. The non persist-able entity cannot be used here

I am trying to filter values for one reference selector based on selection from another reference selector. The Parent-child values. The page parameter is a non persist-able  entity. The parent values are coming from a common lookup entity and the child values from another persist-able entity, The non persist-able entity is having association with both these entities. But when i try to filter the child values based on the selected parent values, I am getting the below error. Invalid path selected for "Constrained by" property. The non persist-able entity cannot be used here. I tried to filter the select-able objects using micro-flow but that is of no help. Can i achieve this using this non persist-able entity or any other directions to achieve this? Please help. Thank you!!
1 answers

I believe you should use a microflow as source for the selectable objects in the reference selector for child object as the non-persistable page parameter rules out using Database or Xpath as source. Create an association between your parent and child (1 parent has multiple childs). Use this association to retrieve all child objects that belong to the parent object (return this list of childs if the parent is filled)

On the reference selector for the parent you should use an on-change microflow that refreshes the non-persistable object. This will re-obtain the list of child objects on your child object reference selector.