Local Parting Surface

1. Add another parting surface part.Add another parting surface part.Click Parting Layout Tools > Add Parting Surface Part..
   Name it Local.
   

2. Place the parting surface part on the UCS as indicated by the arrow in the following image.
   Click OK.
   

3. You can highlight the split direction in the tree through the display area. Select the face indicated below. 
   Right-click and select Highlight Split Direction. The relevant split direction is now highlighted in the tree.
   

4. Right-click the highlighted split direction in the tree.
   Select the Hide Other option to hide all other split directions (only the blue faces remain).