The Bolted Connection dialog box now contains a toggle that supports inserting the connection as individual components or as a sub-assembly into the main assembly.
The Bolted Connection dialog box, as shown below, is enhanced to support inserting components or a sub-assembly into the main assembly: Use the toggle to insert the bolted connection as individual components or as a bolted connection sub-assembly into the main assembly. Previously, these components could only be inserted as a sub-assembly. In the dialog box, click Enables/Disables the sub-assembly structure to toggle between inserting a top level component or a sub-assembly component.
Design tab 
Fasten panel Bolted Connection command:
By default, the toggle
disables the creation of the sub-assembly structure and creates individual parts within your root assembly.
Click the toggle to enable the creation of a sub-assembly
.
For more information on creating bolted connections, see To Create and Insert Bolted Connections.