# Controlled by Parent, master-detail and implicit sharing

*Platform Sharing and Visibility Architect Study Guide · Access to Records · Last updated October 26, 2026 · https://www.certifyforce.com/study-guide/platform-sharing-and-visibility-architect/access-to-records/controlled-by-parent-master-detail-and-implicit-sharing*

How a master-detail relationship makes a detail object's access follow its master (and what the detail loses), how junction objects need access to both masters, when a lookup can be converted, and what built-in implicit sharing gives between accounts and their contacts, opportunities, cases, orders and contracts.

- Certification: Salesforce Platform Sharing and Visibility Architect
- Exam section: Access to Records
- Study guide: https://www.certifyforce.com/study-guide/platform-sharing-and-visibility-architect

**Official exam objective:**

> Given a set of conditions, determine the correct object relationships that support record access sharing requirements.

## What the exam expects

- Choose master-detail or lookup from how a child's access, ownership and deletion must behave.
- Predict who can view or change detail and junction records from master access and the Sharing Setting.
- Know what a detail loses (owner, sharing rules, manual sharing, queues) and when a lookup converts.
- Predict implicit parent and child access between accounts and their contacts, opportunities, cases, orders and contracts.
- Recognise that implicit sharing is standard relationships only and can't be configured.

Key terms: **master-detail** (a relationship where the detail inherits security from the master); **Controlled by Parent** (the default that makes access follow the parent record); **Sharing Setting** (the master access, Read Only or Read/Write, needed to change a detail); **junction object** (a detail with two masters, modelling many-to-many); **implicit sharing** (built-in access between an account and its standard child records).

## Key facts

| Fact | Detail | Source |
|---|---|---|
| Detail sharing | No sharing rules, manual sharing or queues | [Relationships Overview](https://help.salesforce.com/s/articleView?id=platform.overview_of_custom_object_relationships.htm&language=en_US&type=5) |
| Edit a detail | Read or read/write on the master, per Sharing Setting | [Custom Object Security](https://help.salesforce.com/s/articleView?id=platform.dev_security.htm&language=en_US&type=5) |
| Junction read | Read access to both masters | [Custom Object Security](https://help.salesforce.com/s/articleView?id=platform.dev_security.htm&language=en_US&type=5) |
| Lookup to master-detail | Every record needs a value; default becomes Controlled by Parent | [Relationship Considerations](https://help.salesforce.com/s/articleView?id=platform.relationships_considerations.htm&language=en_US&type=5) |
| Limits | 2 master-detail per object, 3 custom detail levels; 10,000 children best practice | [Relationship Considerations](https://help.salesforce.com/s/articleView?id=platform.relationships_considerations.htm&language=en_US&type=5) |
| Implicit sharing scope | Standard relationships only | [Implicit Sharing](https://help.salesforce.com/s/articleView?id=platform.sharing_across_objects.htm&language=en_US&type=5) |
| View All on child | Doesn't give parent account access | [Implicit Sharing](https://help.salesforce.com/s/articleView?id=platform.sharing_across_objects.htm&language=en_US&type=5) |

## Check yourself

- Why can't an admin create a queue for a custom object on the detail side of a master-detail relationship?
- When does access to a contact give a user Read Only access to its Private parent account?
- What happens to a former detail object's default when its master-detail is converted to a lookup?
- Why can't a user transfer an opportunity to a rep who can't see its account?

## Sources

- [Object Relationships Overview](https://help.salesforce.com/s/articleView?id=platform.overview_of_custom_object_relationships.htm&language=en_US&type=5)
- [Custom Object Security](https://help.salesforce.com/s/articleView?id=platform.dev_security.htm&language=en_US&type=5)
- [Considerations for Object Relationships](https://help.salesforce.com/s/articleView?id=platform.relationships_considerations.htm&language=en_US&type=5)
- [Implicit Sharing](https://help.salesforce.com/s/articleView?id=platform.sharing_across_objects.htm&language=en_US&type=5)
- [Implicit Sharing (Designing Record Access for Enterprise Scale)](https://developer.salesforce.com/docs/atlas.en-us.draes.meta/draes/draes_object_relationships_implicit_sharing.htm)
- [Sharing Considerations](https://help.salesforce.com/s/articleView?id=platform.security_sharing_considerations.htm&language=en_US&type=5)
- [Sharing a Record Using Apex](https://developer.salesforce.com/docs/atlas.en-us.apexcode.meta/apexcode/apex_bulk_sharing_creating_with_apex.htm)
- [Platform Sharing Architecture](https://architect.salesforce.com/docs/architect/fundamentals/guide/platform-sharing-architecture)

## About the full unit

The "Core concepts", "Exam traps" and "Worked scenario" sections of this unit, its 13 linked practice questions, and unlimited timed mock exams are included with the Platform Sharing and Visibility Architect pack (USD $19): https://www.certifyforce.com/practice-exams