Merging
Once your robot has been imported, the Merge window ("LDraw Import Wizard") will pop up. The Virtual Robotics Toolkit will automatically attempt to convert your robot into movable and immovable objects; however, the software has difficulty completing this task when the imported robots are extremely complex with many components. In the event that the software cannot identify all of the robot's components, it will categorize them as "Stray Parts".
When the software cannot identify all of the components as movable or immovable, the user must manually merge all of the components which they wish to be immovable.
Tip: When in the Merge Window, only label the components you don't want to merge (i.e. Don't label your movable components). This will simplify the merge process and make it easier to remember which components should be movable and which should be immovable.
To begin the merge process, select the merge button and tick the box for all of the components you'd like to merge together as one. Once finished, click Next.
All you'll need to do after that is assign sensors, motor ports, and assign manual controls, if required.
Troubleshooting
If you find that your robot is not operating correctly after being imported, redo the process of importing the robot and merging components, since components that have been incorrectly merged can cause issues.