Go to customizations page and customize the system.
Click on advanced settings → settings → customizations → customize the system
Select the Entity and click on the form you’d like to add your sub-grid to.
Create the sub-grid to show opportunities
Give your sub-grid a meaningful name and label, click on ‘Show only related Records’, select ‘Opportunities’ from the list of entities and select a view you’d like to show in your sub-grid.
Add nested sub-grid to show contracts
Then, proceed to ‘Controls’ section and click on ‘Add Control’
Choose 'Editable Grid' from the list and click on ‘Add’ button
Click on these 2 radio buttons:
Then click on this pen button
In the pop-up window, select ‘Oneflow Contracts’ entity and select ‘Nested Grid View’ from views
Then click on this pen button:
Choose ‘of_opportunityid(Lookup.Simple)’ from the list:
Click on Ok → Ok
That’s it! You created your grid now and should be all set. Position the grid wherever you need to and don’t forget to save and publish your changes.
View sub-grid on account Account record
You should be able to see the grid on your form now!
If you click on the arrow button when viewing your sub-grid you’ll be able to see all contracts that are associated with you opportunity