Add new lines to an existing CSV

Hello

I want to receive transaction data from Stripe and write it to a CSV. I have managed to do this (my first workflow, yay) :slight_smile:
But now a new CSV is always created and saved for each transaction.

How can I access the existing CSV for a new transaction and add this data?
The previous data should not be overwritten. Each new transaction should be written to a new line.

Kind Regards, Sebastian