we have created purchase order(PO) for a transportation contractor on tonne basis.for eg 1000 tonnes of material.each time around 7 to 8 tons is transported and GRA(goods recd advice) made and invoiced.So in pos 2 , 99 entries on different dates has been made, pos 2 the sequences has touched 99 and when new GRA has to be made it is telling max sequence reached.also the back order of 90 tonnes has vanished.pl help.
whether to insert newline (pos3)in PO, with the balance back order?

Yes,for the balace qty, you have to insert a new position in your PO .