Okay, I think I may need some guidance on this one. Here's what I've done:
1. Get External Data From Other Source > From XML Data File > Click "Resource Files", select my "template.xml" file extracted from the infopath form I had created, renamed "LTCDeterminationOfEligibilityTemplate.xml". Choose "automatically retrieve when form opened".
2. Add some data to fields in this secondary data source.
3. When button is pressed, submit using qRule: SubmitToSharePoint /dssubmit=ShPSubmit /dsname=LTCDeterminationOfEligibilityTemplate
The data submits to the library, but it isn't appearing as an infopath form, it's going in as an xml file. When I examine the file, it's missing these three lines at the beginning that appear in forms I submit directly:
<?xml version="1.0" encoding="utf-8"?>
<?mso-infoPathSolution name="urn:schemas-microsoft-com:office:infopath:LongTermCareEligibilityApp:-myXSD-2018-01-19T19-01-15" solutionVersion="1.0.0.19" productVersion="14.0.0.0" PIVersion="1.0.0.0" href="http://ww-sharepoint/FormServerTemplates/LongTermCareEligibilityApp.xsn"?>
<?mso-application progid="InfoPath.Document" versionProgid="InfoPath.Document.3"?>
If I paste these lines into the xml file that the qRule submitted, they will then open as an infopath form. Note that these lines exist in the original Template.xml that I imported.
Here's a screenshot of how they're appearing:

The 1st item is a qRule submitted xml file with the three lines subsequently pasted in, and it now opens in browser as an infopath form.
The 2nd is an unmodified qRule submitted file, and opens in the browser as an xml file.
The 3rd and 4th are forms submitted from the original infopath form that the template was extracted from.
What am I doing wrong?