Changing from Online accruals to period end accruals

Hi All,

We desires to move away from online accruals for expense purchases and turn on period end accruals. We can change this for a go forward basis,
but how do we handle mid life Purchase Orders in below situations, i.e. is there a way to make them accrue at period end, so we are completely out of online accrual.

1. Open Purchase Orders i.e. no receipt made. eg Ordered 10, received 0 billed 0
2. Purchase Orders where Ordered 10, received 5, billed 5
3. Purchase Orders where Ordered 10, received 5, billed 0
4. Purchase Orders where Ordered 10, received 5, billed 10

Thanks,

Manish