How can I include subform data when submitting a form via email?

How can I include subform data when submitting a form via email?

With regards to the help topic on submitting a form via email:
https://help.creator.zoho.com/Email-Data.html#Adding_form_data_via_e-mail_in_user-defined_format

I have a form with a subform. I need to be able to submit the subform data via email as well - my case a Customer has an Order.

Can you please clarify how I can do this? At the moment my Customer Email Template just shows available fields as:

Field1:
Field2:
Field3:
Order:

Putting values into Order: doesn't seem to work - is there a way to include this data (e.g. Order: Quantity: 3, Sent: False)?

Although I could send two emails (one for the parent record - Customer, one for the child record - Order), there is no way I can see to link the two records together, so the child record will be orphaned.