How can I add more groups in "Group Membership AutoProvisioning Policy" using Powershell?

I need to update some more groups in "Group Membership AutoProvisioning Policy". Is there a way to add these groups using powershell.

e.g. When this policy was created there was three groups in it groupA, groupB and groupC. But now I need to add one more group which is groupX in the same policy which is possible using the GUI but I want to achieve the same using Powershell. 

Any help...