11i Staged Dunning Letter - can we manually send last dunning letter in a set

We are in 11i and setting up dunning letter. We need to use staged dunning method. There are 4 dunning letters in a set. The letter 4 is last letter before send the account to collection agent. We will keep sending 3rd letter every 30 days till determined by manager it is necessary to send the 4th (final notice) to customer. Therefore, we don't want to send the 4th letter systematically. 1) Is there a way to manually run dunning letter, 2) how we can make sure the dunning history gets updated when the 4th letter was sent manually. So,