Display the First Invoice Number on the Invoice Group Advanced PDF/HTML Template

1. Navigate to Customization > Forms > Advanced PDF/HTLM Templates
2. Locate the Standard Invoice Group(Detailed View) PDF/HTML Template and click Customize or find an existing customized one and click Edit
3. Click Source Code
4. Create a table where you want the information to display
5. Between the <td> and </td> tags, insert the following code:

              <#list groupedinvoices_summary as invoice_details><#if invoice_details_index==0>${‌invoice_details.invoicenum}</#if></#list>