One-to-One Parent-Child Relationship Between Instances of Different Record Types
This topic provides details about one-to-one parent-child relationships between instances of different record types. For a general overview of the one parent record type to one child record type relationship, see One Parent Record Type to One Child Record Type.
A parent-child relationship where one parent instance can associate with only one child instance is currently possible only by creating a custom script or workflow. By default, users can associate one or more instances.