This wiki explains how to dimension automatic cuts for group detailing.
Please follow the below steps to achieve this.
1. Open the detail style and go to Dimensioning > Groups > General.
2. Switch on the option Sub parts in sections.There should be a new page should appear underneath the Reference points as a Section.
3. It is recommended to start with the default settings, Right Click (context menu) > Default Settings > Create default settings.
4. Now it should look like this, with reference points set for Shapes, PolyPlates and Connection parts.
The automatic cut should get dimensions now as shown in the below image.
In this way, one can get the dimensions for automatic cuts in the group detailing.