How to: If a user already exits, create the user with a "1" after their name -PowerShell Active Directory

I have a script written here that checks if an AD already exists. If they do exist, then the script lets me know. If they don't, then it creates them:

    if (Get-ADUser -F { SamAccountName -eq $username }) {
        
        # If user does exist, give a warning
        Write-Warning "A user account with username $username already exists in Active Directory."
    else {

##Then it carries on here with creating the user

What I'd like to do is, if they exist, create the user with the same naming convention, but put a "1" after their name. I know this sounds silly.... but I've been asked if that is possible.

And if they don't exist, well, carry on as usual and create them :)

Any help would be appreciated ladies and gents.

Thank you :)

I didn't really touch the commented out parts, but hopefully this gives you an idea. I don't had an AD server handy to test it against to just be aware I can't guarantee its 100%

function validation($User){
    if (Get-ADUser -F { SamAccountName -eq $User.username }) {
        $usernumber = 1
        while (Get-ADUser -F { SamAccountName -eq ($User.username + $usernumber)}){
            $usernumber++
        }
        $NewUserName = $User.username + $usernumber
        Add_User($NewUserName, $User)
        }
        else {
            $NewUserName = $User.username
        Add_User($NewUserName, $User)
        }
}

function Add_User($Username, $User){
New-ADUser `
            -SamAccountName $Username `
            -UserPrincipalName "$Username" + "@MEtest.com" `
            -Name "$Firstname $Lastname" `
            -GivenName $User.Firstname `
            -Surname $User.Lastname `
            -Enabled $True `
            -DisplayName "$User.Lastname, $User.Firstname" `
            -Path $User.ou `
            -OfficePhone $User.telephone `
            -Title $User.jobtitle `
            -AccountPassword (convertto-securestring $Password -AsPlainText -Force) -PasswordNeverExpires:$false -ChangePasswordAtLogon:$True
}

$ADUsers = Import-Csv C:\ps\usercreation.csv

$UPN = "METest.local"

foreach ($User in $ADUsers) {
    validation($User)

        #If this user exists
        Write-Host "The user account $username is created." -ForegroundColor Cyan
        
        #Sleep time to sync for Exchange push
        #write-host Pausing for Exchange Sync....
        #start-sleep -Seconds 300
    
    #Apply licenses to users created in AD then synced to Exchange
        #Set-MsolUserLicense -UserPrincipalName $newuser.UserPrincipalName -AddLicenses UI-OF-LICENSE-HERE   
        #Set-MsolUserLicense -UserPrincipalName $newuser.UserPrincipalName -AddLicenses UI-OF-LICENSE-HERE
        
    }
}

Read-Host -Prompt "Press Enter to exit"

##full script##

$ADUsers = Import-Csv C:\ps\usercreation.csv

$UPN = "METest.local"

foreach ($User in $ADUsers) {

    #Assign the data in the csv to a variable
    $username = $User.username
    $password = $User.password
    $firstname = $User.firstname
    $lastname = $User.lastname
    $OU = $User.ou #This field refers to the OU the user account is to be created in
    $telephone = $User.telephone
    $jobtitle = $User.jobtitle

    #Check and see if the user already exists in AD
    if (Get-ADUser -F { SamAccountName -eq $username }) {
        
        #Warn if the users already exists
        Write-Warning "A user account with username $username already exists in Active Directory."
    }
    else {

        #User does not exist then proceed to create the new user account
        New-ADUser `
            -SamAccountName $Username `
            -UserPrincipalName "[email protected]" `
            -Name "$Firstname $Lastname" `
            -GivenName $Firstname `
            -Surname $Lastname `
            -Enabled $True `
            -DisplayName "$Lastname, $Firstname" `
            -Path $OU `
            -OfficePhone $telephone `
            -Title $jobtitle `
            -AccountPassword (convertto-securestring $Password -AsPlainText -Force) -PasswordNeverExpires:$false -ChangePasswordAtLogon:$True

        #If this user exists
        Write-Host "The user account $username is created." -ForegroundColor Cyan
        
        #Sleep time to sync for Exchange push
        #write-host Pausing for Exchange Sync....
        #start-sleep -Seconds 300
    
    #Apply licenses to users created in AD then synced to Exchange
        #Set-MsolUserLicense -UserPrincipalName $newuser.UserPrincipalName -AddLicenses UI-OF-LICENSE-HERE   
        #Set-MsolUserLicense -UserPrincipalName $newuser.UserPrincipalName -AddLicenses UI-OF-LICENSE-HERE
        
    }
}

Read-Host -Prompt "Press Enter to exit"

P.s. dont bother about all the comments...they are there so it doesn't run certain things while I test

Within your if statement with the warning just add

$username = $username + "1"

And then repeat the code in your else section.

Can always clean it up and place the create account code in a function and call it in each portion of the if statement.

So firstly you dont need to assign your values from The csv to variables, they are already loaded into the object and residing in memory, so you can switch out $username to $user.username repeat it for the add user section, just change the name after the period for the dataset. I think i see what happened, so if you have john doe in the system and another 2 john doe's on your list, the first time it created a john.doe1 and was succesful but the second time it failed. So you need to pull the username string trim it to the last character, do an comparison to see if the last character is a character or number. If a letter then concatenate a 1 if a number add 1 to it and concatenate that number instead. Make sense? On my phone so writing the code and researching the syntax is a pain sorry.