How to show 20m offset ground level in Longitudinal section

Hello,

I want to show 20m offset ground and Level in Longitudinal section while exporting. In attached screen shot you can see line of 20 m offset line is generated but level is not displayed. With the default seed  it show only design line and Level, OGL line and  level of below ground but not 20m offset.

Kindly guide/provide video link to create new seed file to add 20m offset OGL level (LHS and RHS)

Regards