Odoo process is to post consumption after finish production. You enter first total produced, then components consumed.  

Your options is to confirm what has been produced, and then let Odoo create a backorder for the remaining qty.  You can repeat this as many times you need.

If you use work centers / work order, Odoo will automatic create backorders. If not you can set on the operation type wether you want automatic backorder, ask to get a backorder or never create backorders.