I have leveraged the ItemMapsStr of the MemoCopy class to copy all the Delivery Options fields I could find.
What this means is that in addition to requested Return Receipt field, the Create Mail Merge script will now copy fields like Reply To, Reply Date and the High Importance flag from the master email template, where they have been provided.
%REM
Sub ItemMapsStr OVERRIDDEN
Description: Property overridden to copy mail delivery options fields from the email template.
%END REM
Property Get ItemMapsStr As String
ItemMapsStr = MemoCopy..ItemMapsStr & ";ReplyTo;DeliveryReport;ReturnReceipt;RR2" & _
";ReplyDate;DueDateTime;ExpireDate;Importance;tmpImp"
End Property