Custom Zen Cart plugin req for v 1.50

We need a Zen Cart plugin created. * Vendor account creation & login (Multiple Manufacturer sales history) We deal with multiple developers & manufacturers. We require that they have their own login, that they are able to view their own sales in any period, that we (the owners) can also leave messages in their account, raise payment invoices for their monthly earnings. Our manufacturers want to see what sales they've had, what they've been paid, when they will be paid, income & expense basically, and we want the ability to also manually override any payments, or create manual invoices for any deductions of bonuses. The other considerations: * Reward point, gift voucher & paypal fee deductions are calculated over the entire order, not just the one product, so you will also need to be able to run calculations = {Total Product Value only - (Total Order discounts/number of products) = Manufacturer value} * Manufacturers are paid on commission for their products only, and percentages may be variable, depending on bonuses & so on. We do NOT require the manufacturers to have the ability to create their own products, to alter the product prices, or any modifications at all. We are NOT wanting to set up a mini mall. Initially this will be a once off job, however there may be ongoing work in the future.