Calculated Commissions Overide

Is there a way to override the calculated commission?  For example, the commission plan may calculate a commission amount but a sales manager want to override the amount and pay something different.  We can change the amount authorized and paid but it leaves a pending commission on the employee's commission report equal to what was calculated by the plan minus what was authorized and paid.  We want to be able to edit the amount calculated to as to remove the delta from the pending commissions report.

This is important to us because the commission module in NS is unable to calculate commissions the way we need to (gross profit on non-inventory items).  This has forced us to use the commission engine in NS to calculate that commissions are due and populate the calculated amount with a bogus $ amount.  We then manually calculate the commission and authorize and pay that amount.  It leaves us with a difference between the calculated and authorized amounts this leaving a balance (either positive or negative) on the pending commissions reports - even though there will be no additional commissions paid