Since there is no organizer, the short answer is NO.  You could add it as a part of the Final Paragraph in the Client Letter. It would probably be much better to just do a Word Document with Mail Merge from data exported from the program.

 

I create a second letter on client letters (calling it engagement letter).
Then change the settings to point to THAT letter & print/pdf the letter for all clients. Then switch the setting back to the original letter for creating the tax return.