The Replenishment Groups are used by the Replenishment Transfer Rule functionality. Replenishment Groups consist of one or more locations. A location can only belong to one Replenishment Group.
To attach a location to a Replenishment Group, you need to open the Location card, go to the Replenishment tab and fill out the Replenishment Group field.
You can either apply a Replenishment Transfer Rule to individual locations or Replenishment Groups.