使用powershell读取文本替换行同时增加一行

本文是用 az network bastion rdp --name 生成rdp文件后的修改，因为rdp文件中默认时多屏打开VM，本人只想用一个屏幕显示，测试多种方法无法直接获取到命令的结果，修改替换之后在保持成x.rdp文件，如果有知道怎么修改的朋友，请不惜赐教，谢谢！

$basePath = "C:\Users\seare\AppData\Local\Temp"
$fileName = Read-Host "please input file name "
$fullPath = Join-Path $basePath $fileName
try {
    $content = Get-Content -Path $fullPath
    $newLineIndex = 1
    $replaceLine = "use multimon:i:0"
    $newLine = "smart sizing:i:1"
    $linesToInsert = $content[0..$newLineIndex]
    $linesToInsert += $replaceLine
    $linesToInsert += $newLine
    $linesToInsert += $content[($newLineIndex + 2)..($content.Count - 1)]
    $linesToInsert | Set-Content -Path $fileName
}
catch {
  Write-Error "not read $fileName"
}

替换前的内容：

full address:s:ironmanjboxsit:3389                
alternate full address:s:ironmanjboxsit:3389      
use multimon:i:1                                  
gatewaycredentialssource:i:5                      
gatewayusagemethod:i:1                            
gatewayprofileusagemethod:i:1                     
gatewayhostname:s:bst-3f6cac8e-d1cf-46b0-9595-9eef
gatewayaccesstoken:s:eyJhbGciOiJSUzI1NiIsInR5cCI6I
signscope:s:Full Address,Alternate Full Address,Ga
signature:s:AQABAAEAAAChCwAAMIAGCSqGSIb3DQEHAqCAMI

替换后的内容：

use multimon:i:1  --1-->0                                
smart sizing:i:1 --add line

full address:s:ironmanjboxsit:3389                
alternate full address:s:ironmanjboxsit:3389      
use multimon:i:0                                  
smart sizing:i:1                                  
gatewaycredentialssource:i:5                      
gatewayusagemethod:i:1                            
gatewayprofileusagemethod:i:1                     
gatewayhostname:s:bst-3f6cac8e-d1cf-46b0-9595-9eef
gatewayaccesstoken:s:eyJhbGciOiJSUzI1NiIsInR5cCI6I
signscope:s:Full Address,Alternate Full Address,Ga
signature:s:AQABAAEAAAChCwAAMIAGCSqGSIb3DQEHAqCAMI