How to set Estimate quantity at customer account level for a period to track consumption?

Hi team,

We are having a business scenario, where they want to track estimates at customer account level, instead of subscription level.

Ex - A customer may have multiple subscriptions. But the minimum consumption quantity (estimated quantity) within a period, should be set at customer account level, not for each subscription. So, in any deal, if a customer needs to consume 1000 stocks on yearly basis, then that should be calculated after accumulating all usages within subscriptions belong to that customer for a specific year. After accumulating all those usages, if we found that is more than the estimated limit, which was set at customer account level, then the customer should get charged for the excess quantities, otherwise nothing to pay back