Change grouping logic to generate invoices based on Interface Date

Summary:

We have a crucial question regarding the functionality of invoice generation, specifically concerning backdated or rebilled invoices following recent system updates.
Currently, the system is generating invoices based on the Bill From Date. Our business expectation, which we have been working toward, is that if all line items share the same Interface Date, the system should generate a single invoice combining the totals under that specific Interface Date.
We have updated the optional grouping rule to include sales_order_date, and invoices are now being generated based on the Interface Date, which aligns with our core need.
However, we need confirmation on whether this specific functionality will operate correctly for backdated or rebilled invoices. For example, if we perform a rebill of an SAP conversion invoice that includes line items spanning three years, the current concern is that the Interface Date for all those historical items will automatically update to the current date. We need to prevent this update and ensure the system respects the original, historical Interface Dates upon rebilling or backdating.