Dynamically adding properties to object

 public class GenericPaymentMethod<T>
    {
        public int TenantID { get; set; }
        public string Market { get; set; }
        public List<T> CreditCard { get; set; }
        public List<T> DebitCard { get; set; }
        public List<T> BPay { get; set; }
    }
public class EditPaymentMethod
    {
        public GenericPaymentMethod<Multicheckbox> MyProperty { get; set; }
    }
public class Multicheckbox
    {
        public string CheckboxName { get; set; }
        public bool IsChecked { get; set; }
    }

public static EditPaymentMethod GetPaymentMethodDetails(int tenantID) {
            dynamic obj = new EditPaymentMethod();
            obj.MyProperty = new GenericPaymentMethod<Multicheckbox>();

            obj.MyProperty.TenantID = 1000;

            obj.MyProperty.Market = "AU";

            obj.MyProperty.CreditCard = new List<Multicheckbox>(){
                new Multicheckbox { CheckboxName = "Amex", IsChecked = true },
                new Multicheckbox { CheckboxName = "Master Card", IsChecked = false },
                new Multicheckbox { CheckboxName = "Visa", IsChecked = true }
            };

            obj.MyProperty.DebitCard = new List<Multicheckbox>(){
                new Multicheckbox { CheckboxName = "Amex", IsChecked = false },
                new Multicheckbox { CheckboxName = "Master Card", IsChecked = true },
                new Multicheckbox { CheckboxName = "Visa", IsChecked = false }
            };

            obj.MyProperty.BPay = new List<Multicheckbox>(){
                new Multicheckbox { CheckboxName = "Savings Cheque", IsChecked = true },
                new Multicheckbox { CheckboxName = "Credit Card", IsChecked = false },
            };

            for (int i = 0; i < obj.MyProperty.BPay.Count; i++)
            {
                obj.BillerCodes = new List<string> { "AAA", "BBB" };
            }

            return obj;
        }