Maybe this is an unsupported scenario but this is how I am testing my PCF dataset control for NN relationship.
So, my control allows to represent all available records for a NN relationship as checkboxes. User can tick the checkbox and it associates records. They untick the checkbox to disassociate records.
To check that everything works as expected, on my form, I added the same subgrid twice, one with my PCF control, one with standard subgrid. This way, I can check quickly if records are correctly associated.
The problem I found is that refreshing the standard subgrid triggers the updateView method of my PCF but the method receive the records that were visible in the standard subgrid before the manual refresh, but not the ones actually associated.
Let me be more specific : I'm loading my form and can see two checkboxes ticked in my PCF control and two records associated in the standard subgrid.
If I untick one checkbox, it disassociates the record. The subgrid is not automatically refreshed (should it be? do I have to do something to force it being refreshed?). If I refresh manually the subgrid, the updateView method is triggered with both records : the one still associated and the not associated anymore but that was visible in the subgrid before the manual refresh.
It seems like a bug to me (unless I should do something on my PCF to force the other subgrid to refresh automatically): the updateView method should receive only the records effectively associated.