Where: These changes apply to Field Service Lightning for Android and iOS in Enterprise, Performance, Unlimited, and Developer editions.
When: Version 5.0 is available for download on Google Play in January, 2019.
How: Instead of downloading all records on a related list, users are linked to the Salesforce app when they view a particular related list. The related lists on service appointments, work orders, work order line items, and assets are still primed by Field Service Lightning for Android. Easily access online (non primed) data available in Salesforce1.
You don’t need to do anything to enable this feature. Users that don’t have the Salesforce app installed are prompted to download and install it when attempting to open a related record that hasn’t already been downloaded by Field Service Lightning.