Create a new column in Customer's payment method

I dont believe this is very easy as the CustomerPaymentMethodInfo is a projection so not a real DAC/Table. As @sagar07 says can you share your code/package,

This is the source code for the payment method.

 
public class CustomerPaymentMethodInfoExt : PXCacheExtension<PX.Objects.AR.CustomerPaymentMethodInfo>
 {

       #region UsrIsAutopay

       public abstract class usrIsAutopay : BqlType<IBqlBool, bool>.Field<usrIsAutopay> { }
       //[PXDBBool]
       [PXDBBool(BqlField = typeof(CustomerPaymentMethodExt.usrIsAutopay))]
       [PXUIField(DisplayName = "Is Autopay")]

       //[PXDBDefault(typeof(CustomerPaymentMethodExt.usrIsAutopay), PersistingCheck = PXPersistingCheck.Nothing)]

       //[PXParent(typeof(Select<CustomerPaymentMethod, Where<CustomerPaymentMethod.pMInstanceID, Equal<Current<CustomerPaymentMethodInfo.pMInstanceID>>>>))]

       //[PXDBDefault(typeof(Search<CustomerPaymentMethodExt.usrIsAutopay, Where<CustomerPaymentMethod.pMInstanceID, Equal<Current<CustomerPaymentMethodInfo.pMInstanceID>>>>), PersistingCheck = PXPersistingCheck.Nothing)]
       public virtual bool? UsrIsAutopay { get; set; }

       #endregion
   }

Looking through the source, This DAC updates differnetly than most.The persisting event cancels and is handled by a custom persisting event that creates the default payment method. See below:

			protected virtual void _(Events.RowPersisting<CustomerPaymentMethodInfo> e)
			{
				e.Cancel = true;
			}

			#endregion

			[PXOverride]
			public virtual void Persist(Action del)
			{
				using (PXTransactionScope ts = new PXTransactionScope())
				{
					//assuming only one instance of CustomerPaymentMethodC could be inserted at a time
					if (DefPaymentMethodInstance.Cache.Inserted.Count() > 0)
					{
						IEnumerator cpmEnumerator = DefPaymentMethodInstance.Cache.Inserted.GetEnumerator();

						if (cpmEnumerator.MoveNext())
						{
							CustomerPaymentMethod current = cpmEnumerator.Current as CustomerPaymentMethod;

							if (current != null && CCProcessingHelper.IsTokenizedPaymentMethod(Base, current.PMInstanceID))
							{
								var graph = PXGraph.CreateInstance<CCCustomerInformationManagerGraph>();

								ICCPaymentProfileAdapter paymentProfile = new GenericCCPaymentProfileAdapter<CustomerPaymentMethod>(DefPaymentMethodInstance);
								ICCPaymentProfileDetailAdapter profileDetail = new GenericCCPaymentProfileDetailAdapter<CustomerPaymentMethodDetail, PaymentMethodDetail>(DefPaymentMethodInstanceDetailsAll, PMDetails);

								graph.GetOrCreatePaymentProfile(Base, paymentProfile, profileDetail);
							}
						}
					}

					del();

					ts.Complete();
				}
			}

Due to the rest of the screen being read only, it would be easiest to have the field be changed on the customer payment method screen, and then on the customer screen, show the value.