1) loginto OMU portal of master VCN server as admin .
2) choose cluster management
3) select cluster node on navigation tree and click add
choose cluster type as normal if you need cluster members to be video storage MPUs .
4) select cluster members
5) select cluster servers from cluster members
for verification :
click the node in cluster list on the left , the node is expanded and the newly created cluster as below pic :

if you need any calrification , please leave comment