@Oisin Hi, I was really curios if that could work with offline date from an PostGIS layer (but it should). I set up the 1:m relations in my project and they showed up in the attribute form of the parent layer in QGIS. When I tried to add child-datasets in QGIS, postgis refured to save them. In Qfield I got the same behavior. I can save the parent dataset, but I cannot add a child datasets. I get an error thet 'Parents parent primary keys are not available'.

@Oisin Hi, I was really curios if that could work with offline date from an PostGIS layer (but it should). I set up the 1:n relations (as association) in my project and they showed up in the attribute form of the parent layer in QGIS. When I tried to add child-datasets in QGIS, PostGIS refuses to save them. In QField I got the same behavior. I can save the parent dataset, but I cannot add a child datasets. I get an error that 'Parent primary keys are not available'.