PowerShell Script to sync members of distribution group with SharePoint group - powershell

Question

Im in a SharePoint environment where:
distribution lists are in use instead of security lists
can not switch to security list
distribution lists are nested
no user profile sync
So to sync my new SharePoint group "something" I was thinking of running a PowerShell script regulary to fetch all the members hierarchically and put them in the SharePoint group, including checks. Unfortunately I cant install the AD add-in so I installed the Quest AD add-in.
update: I noticed that direct syncing took too long. So I have decided to split the solution: the first AD script output all nested distribution groups (Get-QADGroupMember -Indirect -Type 'group'), although this takes as long as getting all users, this feels safer, since probably this doesnt have to been run that much. Then script 2 read the groups and creates a csv file per group, this is certainly not unique, but with tens of thousands of users, this is the safest way. Then script 3 (underneath) reads the csv files with users and update the SharePoint user group. Then script 4 reads again the usergroup and deletes all the one where the date (in notes) is not equal to the most recent date.
<#
.SYNOPSIS
Syncs All Users in AD distribution Group To SharePoint group:
- Adds new Users
- Updates display name, email when changed
- Deleted Users no longer present
#>
# --------------------------------------------------------
# Variables to Change / Set:
# --------------------------------------------------------
$site = "http://abc-def-ghi:7777"
$SPgroup = "MYCOOLSPGROUP"
$ADgroup = "MYADGROUP"
# --------------------------------------------------------
# Add-SSuser : adds a user to Sharepoint Group
# --------------------------------------------------------
function Add-SSUser {
Param( [string]$account,
[string]$displayname,
[string]$email,
[string]$sitecollectionurl,
[string]$group,
[string]$date)
Get-SPWeb -Identity $sitecollectionurl | foreach-object {
$identityClaimWindowsNTAccount = "i:0#.w|$account"
[Microsoft.SharePoint.SPUser] $ssUser =
$_.EnsureUser($identityClaimWindowsNTAccount)
$_.Groups.GetByName($group).AddUser($ssUser)
$_.Groups.GetByName($group).Update()
Set-SPUser -Identity $ssUser -Web $_.Url -Group $group
# Update properties
$ssUser.Email = $email
$ssUser.Name = $displayname
$ssUser.Notes = "[[$date]]"
$ssUser.Update()
#Write-Host $ssUser.Xml
}
}