下面的代码根据您提供的输入输出所需的结果.

The code below outputs the desired results based on the inputs you provided.

function CombineSkip1($s1, $s2){
    $s3 = $s1 -split ',' 
    $s2 -split ',' | select -Skip 1 | % {$s3 += $_}
    $s4 = $s3 -join ', '

    $s4
}

Write-Output "------Combine files------"

# content
$c1 = Get-Content D:\junk\test1.csv
$c2 = Get-Content D:\junk\test2.csv

# users in both files, could be a better way to do this
$t1 = $c1 | ConvertFrom-Csv
$t2 = $c2 | ConvertFrom-Csv
$users = $t1 | Select SamAccountName

# generate final, combined output
$combined = @()
$combined += CombineSkip1 $c1[0] $c2[0]

$c2PropCount = ($c2[0] -split ',').Count - 1
$filler = (', ""' * $c2PropCount)

for ($i = 1; $i -lt $c1.Count; $i++){
    $user = $c1[$i].Split(',')[0]
    $u2 = $c2 | where {([string]$_).StartsWith($user)}
    if ($u2)
    {
        $combined += CombineSkip1 $c1[$i] $u2
    }
    else
    {
        $combined += ($c1[$i] + $filler)
    }
}

# write to output and file
Write-Output $combined
$combined | Set-Content -Path D:\junk\test3.csv -Force