Dynamics AX 2012 R3 Retail Discount with quantity

Hi All,

I need to setup a Retail Discount which limits the quantity to be sold.

Example:

I have 100 pcs of item A.

I want to apply 30% discount in the item A but I don't want to apply the discount in all 100 pcs.

I want the discount to be apply for 50 pcs only so that I could limit or restrict the items discount to its allocation only.

I checked in the Retail -> Pricing and discounts if I can apply this setting, I could not found it. Is there a setting for this? According to the functional team, there is a setting which limits the discount but not implemented since it is not part of the scope.

Thanks in advance.