insert value to specific line in CSV file

[asheru93]

Hello,

I have a CSV.file that looks something like this:

Carrot
Cake
Other,Values
test1,test
Abc,test,test1
MyString

The CSV values might change.
In case, IF "MyString" is in the CSV file, I want to add two new values('myValue1','myValue2') between first two, so between 'Carrot' and 'Cake' in this case. Then the CSV file will be:

Carrot
myValue1
myValue2
Cake
Other,Values
test1,test
Abc,test,test1
MyString

If "myString" is not in the CSV file then the original file remains the same.