EF6 Code first inheritance from relationship

Question

I need to create a TPH inheritance on an existing database using EF6 and Code first
Table Person
PersonId (Key)
PersonName
PersonTypeId (FK)
Table PersonType:
PersonTypeId (Key)
Description
Category
The field PersonTypeId is the discriminator for the employees and managers, and the classes that I use are:
class Person
public string PersonId {get; set;}
public string  TypeId {get; set;}
public PersonType Type {get; set}
class Employee : Person
class Manager : Person
I use the fluent API to create the relationship between Person and
PersonType like that:
HasOptional(e => e.Type).WithMany().HasForeignKey(f => f.TypeId);
and it works as expected.
Now, I need to Map the inherintance like that:
 m.Requires("Type.Category").HasValue("EMP");
but it doesn't work because I receive an exception saying that the discriminator field doesn't exist.
Any suggestions??

Answer 1

I try to explain me better
m.Requires("PersonTypeId").HasValue("EMP")
It's ok, but it's not what I need 
The mapping discriminator is not the PersonTypeId but the Category field that is in the class(or table) referred by PersonTypeId
I have more than one values of PersonTypeId that has the same category (employee).
If I choose your solution I need that PersonTypeId has more than one value
Like that:
m.Requires("PersonTypeId").HasValue("1").HasValue("2");
but I know that there isn't this possiblity to have more than 1 value for a discriminator. Is it true?
I try to explain me better
m.Requires("PersonTypeId").HasValue("EMP")
It's ok, but it's not what I need 
The mapping discriminator is not the PersonTypeId but the Category field that is in the class(or table) referred by PersonTypeId
I have more than one values of PersonTypeId that has the same category (employee).
If I choose your solution I need that PersonTypeId has more than one value
Like that:
m.Requires("PersonTypeId").HasValue("1").HasValue("2");
but I know that there isn't this possiblity to have more than 1 value for a discriminator. Is it true?