Ability to amend TC broker commission rate after invoicing

Sometimes, I would notice that my TC broker commission rate is wrong only after I have paid some commission to the broker.

In cases like this, I would like to avoid reversing the paid commission invoices, and I'd like to be able to either:

1. Amend the rate of the invoiced broker, and then issue an incremental commission invoice to correct the previously invoiced commission that had the wrong amounts

or

2. Add a new line for the same broker with a different rate on top of the original rate, so that they add up to be the correct rate