Clarification on adjustment of Seniority date

On the Seniority Dates screen, the client wants to adjust the Enterprise seniority date.

The current Enterprise Seniority Date on system is 28/04/1994 but client wants the Enterprise seniority date 05/04/2024 to be displayed on the system.

To adjust the seniority date accordingly, the client must calculate the number of days between the 28/04/1994 and 05/04/2024 (10,935 days) and then subtract the values provided in the field Total Seniority Days Adjusted (10,935 - 28). We must then input the calculated negative value in the field Seniority Days Adjusted Manually for Enterprise seniority date 05/04/2024 to be displayed.

Is it expected behaviour to calculate the adjusted seniority via the calculation defined above using number of days?