how can we create single activity in fusion field service for multiple asset

Summary:

We have asset hierarchy in maintenance,
To create an activity in Fusion Field Service, we can select one asset at a time,
We are selecting top level asset in maintenance and relevant activity is created in field service.
When we complete an activity in FFS, the work done on top level asset is marked as completed even though work on one of the child asset is yet to be completed and maintenance manager has to manually change the relevant data in maintenance
how can we handle this scenario?

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