Add Column to an existing CSV using powershell

Question

Hi Everyone,
I am horribly stuck in building a logic of how can i add a column with certain details in an existing CSV using powershell. I tried many things one of the code is posted below.
The situation is , I have a Folder path ' D:\Exclusion\Final1' it contains a list of CSV's that looks like below:
preprocessed1.csv
CI,Environment
vm-Serv1,Test
preprocessed2.csv
CI,Environment
vm-bkp1,Prod
and so on with same structure..
Then I have another CSV that Contains certain list of Patches and Title
looks like:
Master_Exclusion.csv
Title, Patch
xyz, KB23109
abc, KB432344
yyy, KB321221
What I am Trying to do is to Copy the Column 'Patch' from here and copy them to all the CSVs present at ' D:\Exclusion\Final1'
and  the output would look like :
preprocessed1.csv
CI ,Environment , Patch
vm-Serv1, Test     ,KB23109
                            KB432344
                            KB321221
CI,Environment,Patch
vm-bkp1,Prod,  ,KB23109
                        KB432344
                        KB321221
$filepathex=Get-ChildItem D:\Exclusion\Final1
foreach($fileex in $filepathex)
$exclusion=Import-Csv D:\Exclusion\Master_Exclusion.csv
$list=Import-Csv D:\Exclusion\Final1\$fileex
$list |
Select-Object *,@{Name='Patch';Expression={$exclusion.Patch}}} |
Export-Csv D:\Exclusion\Split2\$fileex -Append -NoTypeInformation
Thanks in Advance for any help or suggestions.

Answer 1

I am extremely sorry for the confusions , actually I am trying to just add a new column named "Patch" to a a list of existing CSV's . the patch column is present in another CSV i need to append it to the list of CSV's
Like
existing csv:
CI,Environment
vm-serv,Test
and another CSV is 
Master_Exclusion.csv
Title,Patch
xyz,kb084932
yrx,KB893748
trw,kb949298
The output would be :
output.csv
CI,Environment ,Patch
vm-serv,Test,kb084932
                     KB893748               
                      kb949298