Subclassing Avro record?
I think I understand what you're trying to do ("subclass" an Avro record in the Avro Schema definition file) but I don't think it's possible.
Instead, a way to do this would be to have EmployeeRecord have a PersonRecord member nested within it, and then the Employee-specific related info following. For example :
{ "type": "record", "name": "PersonRecord", "namespace": "com.yourapp", "fields": [ { "name": "first", "type": "string" }, { etc... } ]}{ "type": "record", "name": "EmployeeRecord", "namespace": "com.yourapp", "fields": [ { "name": "PersonInfo", "type": "PersonRecord" }, { "name": "salary", "type": "int" }, { etc... } ]}