A grouping some restaurant companies use to analyze similar stores often vs a prior year is accomplished in the system with the Comparable (Comp) Stores feature. This allows a company to state which dates each location should be included in the comp store group for reporting. There are many reports that can be filtered to run only for comp stores or non-comp stores.
When a restaurant first opens many restaurant companies don't want to include it in some reports because of its lack of historical sales and the variability of sales in the first few months so its considered non-comparable. Often a store will be considered part of the comp group once its hit a year or 18 months. You have control over when each location should be part of the comp group by setting dates on the Location record.
On the Location form on the General tab populate the field Comp Start Date with the date that location should start become part of the comp store group. There is also a Comp End Date field so if the store should no longer be part of the group you can populate that as well. If there isn't a comp end date then just leave the field blank and it will assume the comp status never ends for this store.
Many reports in the system have the ability filter by a group of locations including Comp and Non-Comp groups. Reports with this option will have a parameter named Filter By where you choose Location Group and then an option for Filter where you can select Comp or Non-Comp. To determine which locations are Comp and Non-Comp on the report, it will use the date you selected to run the report for to compared to the Comp Start and End Date fields on that location.
For example, if you run a report as of 6/30/2016 and choose to filter to the Comp store location group then the report will find all locations where Comp Start Date is prior to 6/30/2016 and where Comp End Date is later than 6/30/2016 or not set at all. The Non-Comp group would be any locations where Comp Start Date is after 6/30/2016 or not set at all, or where Comp End Date is prior to 6/30/2016.
Besides the many reports that can be filtered by these groups, there is also a specific Profit & Loss report format that will show both comp store and non-comp store groups and then a grand total of both groups combined all in one report. This P&L format is named "Comp and Non-Comp Period vs Prior Year".