If you want to create a different pricing procedure and want to maintain different condition records in vk11/vk12 is fine but you need to assign this pricing procedure in OVKK therefore you can create a new document pricing procedure and assign the same with the combination of
Sales area + Customer Pricing procedure + Document pricing procedure -- Condition type
To determine the pricing in invoice level how ever yes i agree in CS its very less requirement its copied from source document
where as your business requirement would have asked for a new or a different pricing procedure at the credit invoice level.
if its pricing in delivery level the freight has to charge in delivery for that u have different pricing procedure