In HyperMesh Post, if you want to easily and quickly import combined load cases, you can do it importing a specific .csv file.

This article will explain the formalism of this file and how you can import it.

The formalism for Linear Combination : 

For Envelope, the formalism is basically the same, the diffence is in the name of the column where you defined the new loadcases, see below in Excel and in a text editor:

In HM Post, it is not possible for the moment to import Step loadcaes.

In the attached video you can see the different steps : 

 - Create the .csv file with the new loadcases

 - Open the model

 - Import results : File > Import > Result > BatchImport (.csv)

 - Combinations will be visible in your browse, and you can use them for post-process.