new past due invoice on oldest letter

Collections at customer level

 Strategie A, containing the following workitems:
 

Dunning letter soft 

Dunning letter unfriendly

Dunning letter angry

> Now my question:
> 1. A customer has a delinquent invoice (nr 1) for which Dunning letter
> unfriendly has been sent
> 2. Now a new delinquent invoice (nr 2) of this same customer appears (days
> late 1)
>
> In the next dunning print: Both invoice nr 1 and invoice nr 2 will be
> added to Dunning letter angry. In other words the customer will not
> receive a Dunning letter soft for the invoice nr 2, that is only a few
> days late. It will be added to the workitem of the invoice with the