Hi,

You need to use the New-HardDisk command. Here is its documentation link: https://developer.vmware.com/docs/powercli/latest/vmware.vimautomation.core/commands/new-harddisk/#C...

In your case, I would do something like :

foreach ($vm in $vms){

  $vm | New-HardDisk -CapacityGB 10 [any_other_settings if needed to be added] | Out-Null

}

Regards,

Maya