We need to be able to add negative amounts to specific line items in our itineraries. Right now if we cancel a helicopter tour or give a discount on a hotel, we have to either zero out the whole price or manually adjust it, which loses all the context of what actually happened.

For example, when we cancel a $10,000 helicopter due to weather, we want to show:

Helicopter Tour: $10,000

Cancelled (weather): -$10,000

Net: $0

Not just change the helicopter to $0 with no explanation.

We also need this for supplier discounts like "1 free night in 8" promotions - we want to show the original price and then the discount separately so clients can see the value they're getting.

This is critical for our business because we have a 7-day rotating roster and if one person refunds something, the next person needs to see exactly what was cancelled and why. Right now it's just confusing and leads to customer disputes.