Vacation earned

I have encountered some issues with how the vacation was being calculated in Alberta for a company that I have recently taken over for.  The vacation was being calculated after the RRSP and Benefit deductions were deducted from the earnings.  In some cases the variance is so slight that there is no adjustment needed however I have several employees that require an adjustment.  The issue I forsee in doing this is that the Gross earnings include income types that are not eligible for vacation pay.  ie. bonus/truck etc.  I have two incomes that I need to calculate the vacation on but I cannot break these out on any one report in Sage 50.  Short of manually entering  the sum of these two incomes from the employee detail tab into an excel spreadsheet and doing the calculation and then making the adjustments.  Other issues, was there a wage increase or vacation rate change in the past year??? Does anyone have any advice on how to do this in an efficient way?