Configuração do persistence.xml e das classes modelo

Bom dia pessoal!

Eu tenho o seguinte cenário: No BD Oracle, algumas tabelas foram criadas com o "usuarioA", e outras tabelas foram criadas com o "usuarioB".

Como eu devo configurar o persistence.xml e as classes "modelo"?

Meu persistence.xml atual:

<?xml version="1.0" encoding="UTF-8"?>
<persistence xmlns="http://java.sun.com/xml/ns/persistence"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/persistence 
    http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd"
    version="2.0">
    <persistence-unit name="default">
        <provider>org.hibernate.ejb.HibernatePersistence</provider>
        <properties>
            <property name="hibernate.dialect" value="org.hibernate.dialect.OracleDialect" />
            <property name="hibernate.connection.url" value="jdbc:oracle:thin:@meuIP/meuBD" />
            <property name="hibernate.connection.driver_class" value="oracle.jdbc.OracleDriver" />
            <property name="hibernate.connection.username" value="usuarioA" />
            <property name="hibernate.connection.password" value="senhaUsuarioA" />
            <property name="hibernate.hbm2ddl.auto" value="update" />
        </properties>
    </persistence-unit>
</persistence>