Discount Pricing Based on Group Discount - and Price on line level in a custom table ..is this possi

I have a discount group on the inventory group and would like to modify the get_custom_price api to return back different prices for the individuals lines being fed into to discount group. I have got it to return back to discount to the entire group ... and modify the api .. but can't see a way to have it return back individual prices. Is this possible?  (The behavior is it feeds into the api the last values in the group and returns back only that price value).  *Note:  I'm also using the oe_order_pub.g_line. to reference the value in the api.