Go to user and enble features for the spliting mrp orders, Just enable 'Allow Splip Manufacturing'.

After that you can see the split button in mrp order form view.

After click on 'split' button, this popup will shown. Here you Select splited by : Number of Qty, Add number of quantity and Select what to do with current order exclued or cancel : Exclude.

After click on split, you can see the order is splited in 3 orders. You can see that orders in smart button.

Splited order list.

In splited order you can see the origin order number.

If Order quantity is Odd and you want to split order with even numbers so it will split order in event numbers and it will make new order for remaining qty.

As you can see the order splited in event qty and remain qty.

Now uncheck split remaining qty.

As you can see in below screenshot, it will split order in even qty and remaining qty will be added in last splited order.

If you want to cancel current order after spliting order, just enable 'Cancel' option in split wizard.

As you can see the current order is cancelled after spliting.

Mrp Order for 13 qty.

You can split order manual quantity, Just add split line with quantity. You can also add more quantity then current orders.

Order splited.

Splited order list.