Exporting sales invoices to .IMP file


I have been tasked to make an .IMP file from custom made "one of a kind" software, for import of Sales Invoice data into Sage 50, Desktop version 2021.1.1.  As far as I can tell, from reading the import file structure guides, both in .Pdf format and in Sage on-line documentation, this is partly simple, but then gets real complicated with the tax info.  Part of the problem is that the tax info is related to how each user has set up their tax table. The other part of the problem is that Sage 50 does not have the ability to export sales invoices to a sales invoice .IMP file, so that all programmers could just use that as an exact perfect example of how to make a properly formatted .IMP file, for import into the same copy of Sage 50.  At the moment, we programmers only are able to export Accounts, Vendors, Customers, Employees.  None of which solve the problem 

After this many years, and with so many people facing this same issue, I'm wondering why Sage has not addressed this.  We are left to go hunting for forth party software, and more expense, to do what should be a simple task.  Which is:  Export Sales Invoices to .IMP format for import to another Sage 50 system.

Question:   Is there a way to export Sales Invoice data from Sage 50 version 2021.1.1, without having to buy more software  ?

If the answer is "No" then I will recommend to the customer that we switch to a different accounting firm, that uses, QuickBooks which has a much simpler process for importing this data.  My customer cannot live without their custom made software, but they can live with changing accounting software.

Frustration level:  10