How to ensure the Mail.dat Field Code MPA-1123 (Mailer ID of Preparer) be left blank if IMBCNT and/or IMBPLT are used in MailStream Plus

All MailStream Plus versions on all platforms.
A mailer's printer wanted to have MailStream Plus (MSP) leave MPA-1123 (Mailer ID of Preparer) blank, because the printer was later modifying the MPA file to put *his* CRID into MPA-1124 (CRID of Preparer).  So he did not want the presorter's Mailer ID to conflict with his CRID.

If you use IMBCNT and/or IMBPLT to have MSP generate the IMB tray/sack/pallet numbers, then the mailer ID used on them will also populate the MPA-1123 field.
(FYI- PA INF subkeyword MDMIMP also populates MPA-1123, so we tried using that and leaving the data area blank, but MPA-1123 still got populated with the Mailer ID from the IMBCNT/IMPPLT.)

A possible suggestion is that when the printer later adds his CRID to MPA-1124, he can also blank out MPA-1123.
UPDATED:  August 14, 2017