I am using hierarchicalforecast to reconcile entity-level forecasts. Does anyone have experience in dealing with new entities entering the hierarchy? Basically, the hierarchy is not constant over time. The specific example is forecasting revenue at these levels: account, sub-business unit, and business unit for 1 quarter ahead. New accounts will enter the hierarchy, and I want to account for that in my higher-level (sub-business unit, business unit) forecasts.