The Object Tree is a visual hierarchy of the syncing depth which can be customised so that you can remove and add Related Objects for each Record Set, ensuring only relevant data is synced to your Org.

Navigate to the Related Objects Tab of a Related Record 

1. Select the pencil icon next to an Object to customise it.

2. Select which Related Objects you would like to be synced for offline access for an Object in the Tree.

All Fields for the Object will be automatically synced for offline access. For example, the Account's Contact field will be synced, however, in order to view the Details for that Contact offline, the Contacts Related Object needs to be selected (as shown above).

To ensure that key app functionality cannot be broken, there are some mandatory Objects that cannot be de-selected when editing Object hierarchy.

3. Once selected, the Object will appear in the Object Tree and will also be available for configuration. 

Each Object has an icon indicating whether there is a 1 to 1 relationship (a single horizontal line) or a 1 to many relationship (three horizontal lines) to its Parent Object in the tree.

4. To enable Chatter Feed and Actions for an Object, edit the Object and select the General tab to select the relevant checkboxes.