JSF + Wildfly dynamically connecting multiple banks

Hello, I have a Web application using JSF + CDI + JPA and WildFly 8 as an application server. So far I'm letting the server manage the transactions, where database connection information, email services, authentication ... are in the server settings (standalone.xml). Now my problem is that I need the system to access multiple databases. So when the client is logged in, he will enter his login and password and also choose the database.

I've done a lot of research and solutions like multi-tenancy did not seem very interesting. I also thought about taking this responsibility from the server, making the connection in the application and still getting uses the injections normally, but I would have to make many changes to the system.

Any tips or ideas on how to solve this problem?

Thank you in advance!

UPDATE

I'm using an approach where I create my EntityManagers dynamically during the same application. So I only change the jta-data-source attribute and so I can change the database I access. It works, but I have 2 problems:

This is an example of what I'm doing to create Entity Managers dynamically (in my application it just changes how to send the name of the database, I just simplified the code):

@ApplicationScoped
public class ApplicationResources {

    @PersistenceContext
    private EntityManager entityManager;

    @Produces
    @Default
    @RequestScoped
    public EntityManager produceEntityManager() {
        Map<Object, Object> props = new HashMap<Object, Object>();
        props.put(PersistenceUnitProperties.JTA_DATASOURCE, DATABASENAME);
        EntityManagerFactory entityManagerFactory = Persistence.createEntityManagerFactory("PU", props);
        return  entityManagerFactory.createEntityManager();
    }

    public void dispose(@Disposes EntityManager entityManager) {
        entityManager.close();
    }
}

After that I removed the @PersistenceContext annotations from my Stateless classes and put the @Inject annotations, so the entityManager happens to be the one I created dynamically. I am setting my datasources in the Wildfly standalone.xml and they are of the xa-datasource type.