AWS IoT SiteWise aggregating metrics data

Hi, In Sitewise I am having a hierarchy defined as below Asset, Wind Turbine 1 - PLC Unit 1 has two metrics defined as below and the values are getting populated. Like wise the same metrics are there for Wind Turbine 2 - PLC Unit 1 and Wind Turbine 3 - PLC Unit 1. All these assets are also receiving the values. The metrics is defined at the model level for these assets. Now the requirement is to perform aggregation of these metrics at the Wind Farm level as shown in the first diagram. I have defined metrics in the Wind Farm model and at the asset level, Wind Farm is showing metric values. I am not sure if the approach followed and formulas used are correct? Please let me know how can I calculate sum of values at wind farm level collected at different wind turbines?