Under course settings of the parent course select Credit Rollup.
Set the minimum number of children required for completion of the parent.
Enable the credits on the children and parent.
Save course.
The max credit on the parent is the upper limit of the amount of credits that can be awarded from the total number of credits eligible to be awarded on the completed children courses.
For automatic credit rollup to the parent, the credit on the parent must be non-variable.
To only display the parent on the transcript navigate to the parent course's settings and select No for show child in transcript.