Will it ever be possible to have sub-subclasses with a different discriminator column from their parent class? If not is there a way to map this without them?

For example I have a legacy table that stores information like this (and it can't be changed):

company_group = 'C', 'I', 'B'
tier_type = '0', '1', '2', '3', '4', '5', '6'

Company = ??, ?? (abstract base class)
BillingCompany = B, 0 (extends Company)
InsuranceCompany = I, 0 (extends Company)
TierCompany = C, ?? (abstract base class extends Company)
Tier1Company = C, 1 (extends TierCompany)
Tier2Company = C, 2 (extends TierCompany)
Tier3Company = C, 3 (extends TierCompany)
Tier4Company = C, 4 (extends TierCompany)
Tier5Company = C, 5 (extends TierCompany)
Tier6Company = C, 6 (extends TierCompany)

Technically the tier companies do not have to be split out but it does help to have them split this way since I can attach methods to the separate classes that help to work with the 6 level hierarchy that the tier columns represent.

The table is laid out as follows:

Company Table:
[code]
company_id
company_name
company_group
tier_type
address1
address2
city
state
zip_code
tier1_name // Only found in tier 1 companies
tier2_name // Only found in tier 1 companies
tier3_name // Only found in tier 1 companies
tier4_name // Only found in tier 1 companies
tier5_name // Only found in tier 1 companies
tier6_name // Only found in tier 1 companies
tier1_company_id // All of these below are only found in tier companies
tier2_company_id
tier3_company_id
tier4_company_id
tier5_company_id
tier5_company_id
[/code]

An example of the mapping I'm talking about would look like this:

[code]
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
<class name="Company" table="company" discriminator-value="">
<id column="company_id" name="companyId" type="string">
<generator class="assigned"/>
</id>
<discriminator column="company_group" type="string"/>
<property name="companyGroup" column="company_group" type="string" insert="false" update="false"/>
<property name="tierType" column="tier_type" type="string" insert="false" update="false"/>
<property name="name" column="company_name" type="string"/>
<component name="address" class="Address">
<property name="line1" column="address1" type="string"/>
<property name="line2" column="address2" type="string"/>
<property name="city" column="city" type="string"/>
<property name="state" column="state" type="AddressStateType"/>
<property name="zipCode" column="zip_code" type="string"/>
</component>
<subclass name="BillingCompany" discriminator-value="B">
</subclass>
<subclass name="InsuranceCompany" discriminator-value="I">
</subclass>
<subclass name="TierCompany" discriminator-value="C">
<discriminator column="tier_type">
<many-to-one name="tier1Company" column="tier1_company_id"/>
<many-to-one name="tier2Company" column="tier2_company_id"/>
<many-to-one name="tier3Company" column="tier3_company_id"/>
<many-to-one name="tier4Company" column="tier4_company_id"/>
<many-to-one name="tier5Company" column="tier5_company_id"/>
<many-to-one name="tier6Company" column="tier6_company_id"/>
<subclass name="Tier1Company" discriminator-value="1">
<property name="tier1Name" column="tier1_name" type="string"/>
<property name="tier2Name" column="tier2_name" type="string"/>
<property name="tier3Name" column="tier3_name" type="string"/>
<property name="tier4Name" column="tier4_name" type="string"/>
<property name="tier5Name" column="tier5_name" type="string"/>
<property name="tier6Name" column="tier6_name" type="string"/>
</subclass>
<subclass name="Tier2Company" discriminator-value="2">
</subclass>
<subclass name="Tier3Company" discriminator-value="3">
</subclass>
<subclass name="Tier4Company" discriminator-value="4">
</subclass>
<subclass name="Tier5Company" discriminator-value="5">
</subclass>
<subclass name="Tier6Company" discriminator-value="6">
</subclass>
</subclass>
</class>
</hibernate-mapping>
[/code]