Since you provided receipts and your friends are thus claiming this child care expense, you must claim this income (I mean you would legally have to claim it regardless but it would be more under the table otherwise).

You need to fill out T2125 Business and professional income reporting form. Read https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/daycare-your-home.html for more details. There are expenses you may be able to claim.