AbleCommerce Shopping Cart Software

Hello, can anyone provide some guidance on how to implement manufacturer hierarchies? For example, Manufacturer B is a child to Manufacturer A. I'm thinking of using ac_CustomFields to hold the reference ID to the parent manufacturer, but this seems kind of messy.

Is there a way to add arbitrary line-item and order discounts to orders? Say I'm creating a phone order, and I decide to give the customer 25% off his order. I don't see a way to do this as is.