Unless something has changed, there will only be one combined client letter.  They show up as separate letters in preview, which is deceiving, but actually print as one combined letter.

My preference has always been to provide separate filing instructions for each return, which is much clearer for clients to read.  Since there is no option in ProConnect to separate these letters, however, we have had to produce our own for each return, which is not productive at all.

In Proseries I deleted the page break between the federal and state letters so that they print on one sheet