Can I claim child care expenses for payments made to a friend who has not provided receipts?

Why is your friend not providing a receipt? What agreement was in place? If you believe that she was to provide you a receipt, you can claim and include her telephone number in place of sin#. If you ever get an audit, just explain  and cra can call and verify the info with your friend.

If you ever get audited you would need to show proof of expenses by providing a receipt. If there is no receipt Cra would adjust your return and remove that expense.