For MFS with NRA spouse with no SSN, in ProSeries put "NRA" as Spouse's Last Name and no other Spouse info. Then when e-filing, uncheck the "Enable conversion error checking" box under Homebase/E-file/Electronic Filing/Convert-transmit Returns & Extensions/Convert & Transmit selected returns/extensions.

If anyone knows how to make this work for state returns (the above works for Federal), please advise.