BS06 for mid-year

We are doing a bi-weekly payroll and benefits are taken each payroll. If an employee is eligible for benefits on 2/1/2015 but doesn't actually enroll until 2/15/2015, the number of paychecks left isn't calculating correctly,it is calculating from their eligibility date and not from the date they are going through new hire enrollment. I had this fixed at my previous employer but I don't remember how I did it. The cycles start at 26 for the year. If anyone can help I would appreciate it.