I want to pay for iCloud storage separate from family sharing plan

My son is allowing me to share his family plan for Apple Music so that my daughter and I can have access. However, we pay separately for iCloud storage on MY credit card. Our phones keep giving us notifications that we need to update our card info (but it is his card since he is the organizer for the family sharing plan - my credit card is listed as "additional"). I want to pay separately for the iCloud storage but let him pay for the Apple Music. Is this possible?