Purchase order To STO

HI,

We perform procurement at one plant for all our plants(strange reasons).

We use STO to move the stock from one plant to other. Is there a standard way to crate a STO automatically when ever we create a PO to vendor.

I am aware that I can use Messages, Idocs and Custom enhancements for this. but I am looking for a standard way of doing this.

Is there any way I can create an STO when ever there is a purchase order with specific selection?

Thanks