Core data relationship confusion -

I am creating a core data model, and I have a client unit whose placement unit An appointment can change in one transaction (if it has been paid for etc.), and I have to keep track of the appointments of customers who have turned into transactions (where the transaction is a unit with other attributes). A customer can have multiple transactions, and there may be many customers of one transaction (optional). If I have connection between transaction and client, I do not think that in a way I can find out which of the appointments has changed and which is not ... With any help, How can I set the model to be thanked so thank you

I think that There are more than one way. This is the one which works for me:

If the transaction is another entity, and there is only one relation to the transaction of appointment. If you do not pay, you can leave the transaction unit. If payment is made, then you establish the transaction and link to your relationship with the appointment and the client. By checking that the transaction for your appointment is zero or not, you know whether it has turned into a transaction or not.