Add a relation between records in a Business Record diagram
Link two records by specifying a relationship between their fields. One record in the
pair is considered the parent or master record, and the other record is considered to be the
child record.
Steps
Right-click on the field in the first record (this will be the child record).
Select Add Relation To.
Drag the arrow and drop it on the field in the second record (this will be the
master record).