ASP.NET MVC Existing project changes

I have a running MVC website in which i want some additions/modifications. Functionality already working There are 3 type of accounts (Admin, Reseller, Client), Admin account can add Client and can convert any account from Client to reseller account and reseller account can add Client (contact details, MaxUser, Expiry date etc...). Currently Client/Reseller is paying amount and once the amount is paid the expiry date field of the Client extends 1 more month. Additions Required. 1. Client/Reseller need to pay amount for updating MaxUser field on pro rata basis. 2. Reseller can select multiple clients and then create a Unique Group (GRP0001) and it will be saved in database after paying the pre-decided amount per client bases (example reseller has selected 5 clients then first time each client added in group will have 7 days expiry from current date after that reseller will pay amount to extend the date for 1 month to continue the group, if new client need to add in an existing group then he will have to pay pro rata bases ) I will give access on Github repository, you need to update it directly.