Form grid syncronisation

Hi guys

For the experienced ones of you, this will be an easy one.

The standard form, PriceDiscActual, we want to make a change to.

When you are in the Details tab, we want the price-disc grid to filter the line discount grid, such the linedisc grid only shows data based on the selected price-disc line.

The two grids are designed to show the prices and discounts separately for a selected customer/item.

How a price line is related to the discount line? Can you elaborate?