Q: I want to see my family members on the same apple account but cannot. Why?

The Find My Friends app sees each iCloud ID as a "person".  To see your family members, all but one of the devices needs to set up a secondary iCloud account.  To do this, on each device go to Settings>Mail,Contacts,Calendars...tap Add Account and select iCloud from the list, tap Get Free Apple ID at the bottom and follow the instructions to set it up.  You don't need to turn on any data syncing with this secondary account; you are only creating it in order to have unique iCloud ID for each device.  When finished, you can identify each of your family members by their unique secondary iCloud account ID in the Find My Friends app.  (Identify the device without the secondary account by the primary account ID.)