This is probably old news to many folks, but I also discovered today that it is possible for all family members to Co-own an Apple Credit - this is not the same has having a family member able to just charge on an account. We prefer this because with a co-owned account we do not have 2 separate credit card bills and statements.
The various status options have some age restrictions and family member status requirements.
Here is a link to some information.
Set up Apple Card Family and add a co-owner and participants - Apple Support.