Hi @ELJ_CPA thanks for posting and nice to see you here! Support is open today and they would be able to take a look at this with you. You can see contact information here. The hours for today, September 14, 2025 9:30 AM 2 PM PT. 

We look forward to seeing you around the community. 

September 14 is not the best day to be learning the rules of electronic filing for a return due the next day.  The Regulation requiring that statement was written in 2000 or earlier, in the days of paper business returns.  But now, all the answers are in Pub 4163.  See pages 60-62.  You just need to learn them.  

3.26 Creating Elections/Disclosure Statements Required by Regulations or Publications
MeF requires all disclosure statements and elections to be included in preparation software and transmitted to the IRS in one file.
To allow companies to add additional information on their return, IRS created a “General Dependency”
Schema. The General Dependency has a defined format and should be used by the taxpayers to report
most disclosure statements and elections required by regulations or IRS publications. The General
Dependency Schema format is provided to Software Developers for their preparation software, and
developers should provide instructions for completing this Schema to its users.

3.27 Preparing Elections and Disclosure Statements That Require Supporting Data
Some elections and disclosure statements require supporting data that cannot be entered into a General
Dependency Schema. IRS allows this data to be submitted as a PDF file. The actual disclosure statement and election must be entered into the required format, and only the supporting data may be submitted as a PDF file.

While I appreciate your detailed assistance very much, the snark about "September 14 is not the best day to be learning the rules of electronic filing for a return due the next day" is not helpful. Client was supposed to provide the appraisal this weekend and I am just trying to cover all bases, since the appraisal has not yet been received.

Also, PTO does have provisions for one to easily tick a box to add the appropriate header to page 1 of Form 1120S in accordance with Rev. Proc. 2013-30 for late Subchapter S elections, so it is not unreasonable to expect the same for other items required to be stated on the face of a partnership return. 

Based upon a discussion with PTO support, the PDF attachment under 1.743-1(k)(5) will need to be made in PTO using the "defaults to main form" where one typically links an attachment to the return. 

My comment may not be helpful to you, but it may remind others that they should learn the procedures before they need them.