Can Family Sharing members use my credit cards on Apple Wallet?

No member of Family Sharing group can see or use any payment method you’ve added to your Wallet.

If you’re the group organizer of the Family Sharing group, you’re responsible for all Family Sharing group purchases on iTunes, App Store etc. if Purchase Sharing is enabled.

If you want to share your Apple Card Mastercard, you can add anyone as a Participant (Authorized User).

Set up Apple Card Family and add a co-owner and participants - Apple Support