Billing unactive orders

Hi to all,

I have huge problem with billing some specific orders. I have to create bill for order that is 3 positions. Positions are created with unlimited change. I need to create 2 separate bills for one positions, that isn't active any more. I can't change Billing to date. On active position I can change that date and create bill with specific billing date. How can I change billing to date on position that isn't active any more?

This is pretty urgent,

Duu0161ko u0160orak