Group membership payment needs to include manager of account

At the moment group memberships only allow payment for the child seats, not the manager of this account who also has full access to the group membership content.

Example: 1 manager and 3 child seats is 4 accounts total, but the payment is for 3 accounts. Making the manager a free member.

Need: The option to include the manager of the group membership in the payment option, making the 1+3 a payment for 4 accounts.