Storage plan
Doesn’t the family plan supersede the need for an additional 299 per month storage charge
Question marked as
If there is a shared iCloud Storage plan (note that is an option and doesn't happen automatically with Family Sharing) and if you have your own upgraded plan, you then have the option to stay with your own plan or join the shared plan. See the sharing instructions in the "Share iCloud+ with everyone in your family" and switching instructions in the "Switch from your personal iCloud+ plan to your family plan" section of Share iCloud+ with your family - Apple Support
Also note the following from that support article:
If a family member is already paying for their own iCloud+ plan, they can choose to switch to your plan or keep their own and still remain part of the family. When they switch to the shared family plan, they get a refund for the remainder of their personal plan. They can't keep their current plan and use the shared family plan at the same time.