The system uses the date of hire for seniority, which allows many of the programmed tiebreakers to occur. However, since many people are hired on the same date, it can make seniority difficult to aware.
The best way to circumvent this problem is to stagger the hire date.
Steve, Jack and John were all hired on the same day. When inputting their hire dates into the system, I put Jack in on the actual date of hire, 1/1/2018. John would be given the date of 1/2/2018 and Steve would get the date of 1/3/2018. By doing this, the system is able to use it's defaulted seniority as a tiebreaker without actually having a tie. It is up to you how you determine who is given which date, but inputting the date of hire in this method will make the system more efficient when the same people have the same hire date.
You can add/edit hire dates by going into the Employees module > add/edit Employees > select the blue edit employee pencil > Time-Off Accrual. From there you will find the employee Hire Date field.