How to Use Notion Relation Property With Sub-Item Property Inheritance

When you link two databases in Notion using a Relation property, you often need to display or calculate information from the linked item without manually copying it. The Sub-Item Property Inheritance feature allows a child database item to automatically inherit a property value from its parent item through the relation. This article explains how to set up a relation between two databases and configure Rollup or Lookup properties so that the child item inherits a specific value from the parent. You will learn the exact steps to create the relation, choose the correct Rollup formula, and avoid common configuration errors that break inheritance.

Understanding Relation Property and Property Inheritance in Notion

A Relation property in Notion links two databases, allowing items in one database to reference items in another. This creates a parent-child connection: the item in the source database is the parent, and the item in the target database is the child. For example, you can link a Tasks database to a Projects database so each task belongs to a specific project.

Property inheritance occurs when a child item automatically displays a property value from its parent item through the relation. Notion provides two property types to achieve this: Rollup and Lookup. A Rollup property can aggregate multiple related values or show a single value from the parent. A Lookup property directly pulls any property from the related item into the current database. Neither requires manual data entry in the child item.

To use inheritance, you must first create a Relation property between the two databases. After that, you add a Rollup or Lookup property in the child database and configure it to read from the parent. The child item then inherits the selected property value from its linked parent item.

Steps to Create a Relation Property and Configure Property Inheritance

Follow these steps to link two databases and set up inheritance using a Rollup property. The example uses a Projects database and a Tasks database where tasks inherit the project name.

1. Open the child database and add a Relation property
   Go to the database that will contain the child items, for example the Tasks database. Click the + button in the last column header. Select Relation from the property type list. In the dialog that opens, choose the parent database, for example Projects. Click Create relation. A new column with the relation name appears in both databases.
2. Link a child item to its parent
   In the Tasks database, click the Relation cell for a specific task. A menu shows all items from the Projects database. Select the project this task belongs to. The relation cell now shows the linked project name. Repeat for each task item.
3. Add a Rollup property to the child database
   Click the + button in the last column header of the Tasks database. Select Rollup from the property type list. A Rollup property configuration panel opens.
4. Configure the Rollup property to inherit the parent value
   In the Rollup configuration panel, set Relation to the relation property you just created, for example Projects. Set Property to the parent property you want to inherit, for example Project Name. Set Calculate to Show Original. This displays the exact value from the parent without any aggregation. Click Done. The Rollup column now shows the inherited project name for each task.
5. Verify inheritance by editing the parent
   Open the Projects database. Edit the name of a project that has linked tasks. Return to the Tasks database. The Rollup column automatically updates to show the new project name. No manual update is needed in the child items.

Using a Lookup Property Instead of Rollup

A Lookup property works similarly but pulls the value directly without a calculation step. To add a Lookup property:

1. Add a Lookup property
   In the child database, click the + button and select Lookup.
2. Select the relation and source property
   In the Lookup configuration panel, set Relation to your relation property. Set Property to the parent property you want to inherit. Click Done. The Lookup column now displays the parent property value for each child item.

Lookup is simpler but does not support aggregation. Use Lookup when you need to display a single value from the parent and do not require calculations or grouping.

Common Mistakes and Limitations When Using Property Inheritance

Rollup shows empty or incorrect values

This occurs when the Relation property is not configured correctly or the child item is not linked to a parent. Open the child database and check the Relation column. If a cell is empty, the item has no parent link. Click the empty relation cell and select the correct parent item. The Rollup value will then appear.

Rollup shows an aggregation like “2 items” instead of the parent value

The Calculate setting in the Rollup property is set to a count or sum instead of Show Original. Open the Rollup property configuration, set Calculate to Show Original, and click Done. The Rollup will then display the exact parent property value.

Child item inherits the wrong property

The Rollup or Lookup property is pointing to the wrong source property in the parent database. Open the Rollup or Lookup configuration and verify the Property field. Select the correct property from the parent database. The child items will immediately update to show the correct inherited value.

Inheritance does not update when the parent value changes

This happens if the Rollup or Lookup property is accidentally converted to a text property. Rollup and Lookup properties are dynamic. If you manually type in the Rollup cell, Notion converts it to a text property and breaks inheritance. To fix this, delete the converted property and add a new Rollup or Lookup property following the steps above. Do not type in the Rollup or Lookup cells.

Relation property does not appear in the Rollup configuration

The Relation property must exist in the child database before you can create a Rollup. If the relation is missing, go back to the child database and add a Relation property as described in step 1. After the relation is created, the Rollup configuration will list it in the Relation field.

Rollup vs Lookup vs Formula: Property Inheritance Methods Compared

Item	Rollup	Lookup	Formula
Purpose	Display or aggregate a property from a related item	Display a property from a related item directly	Compute a value using properties in the same database
Inheritance support	Yes, through Show Original calculation	Yes, pulls value from related item	No, cannot reference properties from other databases directly
Aggregation options	Count, Sum, Average, Min, Max, Show Original	None	Mathematical, logical, and text functions
Update behavior	Updates automatically when parent changes	Updates automatically when parent changes	Updates automatically when any referenced property changes
Use case	Inherit a single value or aggregate multiple related items	Inherit a single value without aggregation	Calculate values within the same item, not across databases

For property inheritance across databases, use Rollup with Show Original or Lookup. Formulas cannot reference properties from other databases and are not suitable for inheritance.

You can now link two databases with a Relation property and configure Rollup or Lookup to automatically inherit property values from the parent item. This removes the need to manually duplicate data across databases. To extend this setup, try using a Rollup with Count to see how many child items are linked to each parent. For advanced use, combine Rollup with a Formula property to create calculated fields that depend on inherited values.