The form allows you to add a new/edit an existing series of payment reminders via email.
The edit page is completely identical to the add page except for the header (Edit instead of Adding).
If it is necessary to enter/change the name of the conversation, then select the products for which the chain of reminders is created (tick checkboxes):
Then click the Save button.
You will be taken to the Payment reminders via email page where a new (empty) or modified series of letters will appear in the list of letters.