If you want to select a location for a note, you will need an association between DeliveryNote and Location entities. Once that is created, you can add a reference selector to your Create_DeliveryNote page. If the DeliveryNote_Partner association is populated, you can use that association to constrain the values that are shown as options in a reference selector for the DeliveryNote / Location association.
Hope that helps,
You have to use the reference selector for this.
Which renders as a drop down. Though the dropdown widget is only suitable for enums and booleans
On the Create_DeliveryNote page you have a data view for editing the DeliveryNote page parameter.
Inside that data view, add another data view for the Partner of that DeliveryNote.
Inside that data view, add a reference set selector for Location.