How to open/create new salesorder in button click

Dear Experts,

I want to open/create a new sales order on a button click of sales order page.

Below is my business scenario:

I have a sales order A with 2 items item1 and item2. Item1 is available and item2 is out of stock. In this case I need to add a button in sales order page .On click of this button a new order B should be created(split the items of Order A by creating Order B). Order B will have same information of Order A.

How to achieve this functionality.

Thanks,

Resmi