1. Go to your contract and amend it.
2. Open your amendment quote and click Amend Assets.
3. Select your bronze package and then your upgrade bronze to silver product.
4. Change the quantity of your Upgrade Bronze to Silver product from 1 to 4. Salesforce CPQ reduces the quantity of your Bronze IT Package to 80.
5. Save your amendment quote and contract it. Your contract contains 80 Bronze IT Packages and 20 Silver IT Packages.