Packer image with multiple drives

I am working on building an image that will house default items in a secondary drive.

For instance:
C:\ Main OS
E:\ Secondary Drive.

I have it where it will build the drive, but when running packer, I am not sure how to get it to install the OS on the C: on its own, it prompts for selection.

Here is the packer Cod I have so far, I am not sure how to change the ISO paths to install on the correct drive. Could this be in the autounattend.xml?

source "vsphere-iso" "SQL" {
  CPUs                  = "${var.vm-cpu-num}"
  RAM                   = "${var.vm-mem-size}"
  RAM_reserve_all       = true
  cluster               = "${var.vsphere-cluster}"
  communicator          = "winrm"
  convert_to_template   = "true"
  datacenter            = "${var.vsphere-datacenter}"
  datastore             = "${var.vsphere-datastore}"
  firmware              = "bios"
  floppy_files          = ["autounattend.xml", "./scripts/enable-rdp.cmd", "./scripts/enable-winrm.ps1", "./scripts/install-vm-tools.ps1", "./scripts/set-temp.ps1", "./drivers/", "./drivers/pvscsi.inf", "./drivers/pvscsi.sys", "./drivers/txtsetup.oem", "./scripts/sqlSetup.ps1", "./scripts/install-bginfo.ps1", "./distribution/"]
  folder                = "${var.vsphere-folder}"
  guest_os_type         = "windows9Server64Guest"
  insecure_connection   = "true"
  iso_paths             = ["${var.os_iso_path}", "[] /usr/lib/vmware/isoimages/windows.iso"]
  cd_files              = ["${var.cd_iso_path}"]
  password              = "${var.vsphere-password}"
  remove_cdrom          = false
  username              = "${var.vsphere-user}"
  vcenter_server        = "${var.vsphere-server}"
  vm_name               = "${var.vm-name-sql}-${legacy_isotime("20061020304")}"
  winrm_password        = "${var.winadmin-password}"
  winrm_timeout         = "2h"
  winrm_username        = "Administrator"
  disk_controller_type  = ["pvscsi"]

	network               = "${var.vsphere-network}"
	network_card          = "vmxnet3"
	disk_size             = "${var.vm-disk-size}"
	disk_thin_provisioned = true	  
    disk_controller_index = 0
	disk_size             = "${var.vm-disk-size}"
	disk_thin_provisioned = true	  
    disk_controller_index = 0

# a build block invokes sources and runs provisioning steps on them. The
# documentation for build blocks can be found here:
build {
  sources = ["source.vsphere-iso.SQL"]

  provisioner "powershell" {
    inline = ["A:/install-bginfo.ps1"]
    provisioner "powershell" {
    inline = ["A:/sqlSetup.ps1"]

  provisioner "windows-update" {
	search_criteria = "IsInstalled=0"
    filters = [
      "exclude:$_.Title -like '*Preview*'",
    update_limit = 25


Yes, I think this needs to be in your autounattend, though off the top of my head I’m not sure how to write it. This example might get you started though: