The subassembly creation command is available in the Assembly Structure window and in the context menu of the fragments selected in the 3D Model window. This command allows you to change the hierarchy of fragments in the assembly structure: place the fragments in the subassembly by changing their level to n-1, where n is the current fragment level.
In the Assembly Structure window, select the fragments to be placed in a separate subassembly and click the Actions icon, select the Create subassembly command from the list of commands.
The detail creation dialog box appears. To create a new assembly unit, select the second option.
You can see the assembly structure changes in the Assembly Structure window. The selected fragments moved to a lower level, and a new assembly unit appeared in their place.
The fragments in the new subassembly will retain their transformations according to the assembly from which they were placed in the new subassembly. The reference elements will retain both the source of the reference geometry and the source of the document parameters.
If the fragment being moved down a level was adaptive to the assembly (subassembly), then it will cease to be adaptive, because the connection "Assembly > fragment of the first level" will be broken.