Thanks for you quick answer.
As you know in Belgium and in France you need proof that goods did return and that you gave the money back, this is done by the means of a credit note. The goods are back into stock but most important you have a trace for your financial statement that the credit note is the reverse booking for the invoice. This is also important for the customer, he needs also a proof he returned the goods and he got his money back and also they have proof also for their financial statement too.
The refunding is a separate issue and this should be done by the party who is collecting the money for your transaction, in our case we are using in the beginning the manual payment, the customer pays with bank transfer so our refunding will be done by ourselves.
I hope this clarifies my initial question, how can I set up credit notes, can I work with refunded status on a order and can i generate a credit note which linked to the original order.