- Go to Setup > Customization > CRM Fields > Click New.
- Enter a value on Label field.
- Choose List/Record on Type field.
- Choose Transactions on List/Record field.
- Check on Store Value field.
- Check on Record is Parent.
- On Applies to > check on Event.
- On Display > Parent Subtab assigned your preferred subtab.
- On Sourcing & Filtering > Set Filter Using to Type.
- Set Value is field to Sales Order.
- Click Save.
