Seniority Dates should be before date than the hire date for an employee

We have an acquisition of company ABC, In migration the recommendation is that the hire date of all the ABC employees will be 1st Aug 2025 but the seniority dates should be the respective dates considering their experience in company ABC, which will be a back dated.

Currently we are using the version V3 for seniority dates in our system, and In 'Seniority Dates' page using HDL we are able to update the Enterprise seniority date to respective back dates using ManualAdjustmentDays which also populate details of Manual adjustment days in 'Seniority Dates' pages, but the expectation is not by the adjustment but Enterprise seniority date should be respective back dates and should not show any value for Manual Adjustment Days in 'Seniority Dates' page.