In ASP.NET MVC, how do you map many one-to-many relationships?

If you are using code-first (I think you want this, else, you have to edit your Q), the first way is the way explained below:

Entities:

public class Address {
    [Key]
    public int Id { get; set; }
    public string Line1 { get; set; }
    public string Line2 { get; set; }
    public string Line3 { get; set; }

    public virtual Customer Customer { get; set; }
    public virtual StoreLocation StoreLocation { get; set; }
    public virtual Employee Employee { get; set; }

    public int? CustomerId { get; set; }

    public int? EmployeeId { get; set; }
}

public class Customer {
    [Key]
    public int Id { get; set; }
    public string Name { get; set; }
    public virtual ICollection<Address> Addresses { get; set; }
}

public class StoreLocation {
    [Key]
    public int Id { get; set; }
    public string ShortCode { get; set; }
    public string Description { get; set; }
    public virtual Address Address { get; set; }
}


public class Employee {
    [Key]
    public int Id { get; set; }
    public string Name { get; set; }
    public DateTime Dob { get; set; }
    public virtual ICollection<Address> Addresses { get; set; }
}

DbContext inherited class:

public class ManyOneToManyContext : DbContext {

    static ManyOneToManyContext() {
        Database.SetInitializer<ManyOneToManyContext>(new ManyOneToManyInitializer());
    }

    public DbSet<Address> Addresses { get; set; }
    public DbSet<Customer> Customers { get; set; }
    public DbSet<StoreLocation> StoreLocations { get; set; }
    public DbSet<Employee> Employees { get; set; }

    protected override void OnModelCreating(DbModelBuilder modelBuilder) {

        modelBuilder.Conventions.Remove<IncludeMetadataConvention>();

        modelBuilder.Entity<Customer>().HasMany(c => c.Addresses).WithOptional(a => a.Customer).HasForeignKey(a => a.CustomerId);

        modelBuilder.Entity<StoreLocation>().HasRequired(s => s.Address).WithOptional(a => a.StoreLocation).Map(t => t.MapKey("AddressId"));

        modelBuilder.Entity<Employee>().HasMany(e => e.Addresses).WithOptional(a => a.Employee).HasForeignKey(e => e.EmployeeId);
    }
}

Context Initializer:

public class ManyOneToManyInitializer : DropCreateDatabaseAlways<ManyOneToManyContext> {
    protected override void Seed(ManyOneToManyContext context) {

    }
}

That will create the db-schema below: Let me know if you have any questions or need clarifications on any part.