class Customer
{
    public int Id { get; set; }
    [MaxLength(512)]
    public string Name { get; set; }

    public Customer Associate { get; set; }
    public int AssociateId { get; set; } 
    public Customer Associated { get; set; }
    
    public List<Address> Addresses { get; set; }
}

class Address
{
    [MaxLength(256)]
    public string Name { get; set; }
    [MaxLength(256)]
    public string Line1 { get; set; }
    [MaxLength(256)]
    public string Line2 { get; set; }
    [MaxLength(85)]
    public string City { get; set; }
    [MaxLength(12)]
    public string ZipCode { get; set; }
    [MaxLength(128)]
    public string Country { get; set; }
}

class MyDbContext : DbContext
{
    public DbSet<Customer> Customers { get; set; }
    
    public MyDbContext(DbContextOptions<MyDbContext> options)
        : base(options)
    {
    }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<Customer>().OwnsMany(e => e.Addresses);
        //modelBuilder.Entity<Customer>().HasOne(e => e.Associate).WithOne(e => e.Associated);
    }
}

context.Set<Customer>()
    .Where(c => c.Id == 3)
    .SelectMany(c => c.Name == "Test" ? c.Addresses : c.Associate.Addresses)
    .ToList();