When trying to select a shape in 2D for modification purpose, it gets selected along with its group rather than a single part. This wiki will guide you to how to resolve this concern.
1. When one tries to select the one part from the group and whole group gets selected because the option ‘Select group as whole' is turned on.2. Unchecking this option or turning off this toggle will resolve your concern.
3. Make sure that, the ‘Select group as a whole’ PS toggle is turned off.
4. Also, one can control the same option from ProSteel options as well.
5. Go to ProSteel options by holding rightclick>options. Then under ‘options’ tab make sure that ‘Select Group as a whole’ is unchecked.
6. After unchecking this option/toggle, you will be able to select the separate part from the grouped structure.