For your existing direct debits: You don't need to do anything at all. It's up to your service provider (the creditor) to make the necessary changes.
To point a direct debit towards your BGL BNP Paribas account, please contact your service provider (the creditor).
To change the parameters of your direct debits (frequency, list of authorised creditors, amounts, etc.) please contact your financial advisor at your branch.
For all new direct debits, you will need to sign a European direct debit mandate, which you can obtain from your service provider.