PM Order adding more components

Hello ALL

for example:-

(1) i created one PM order and created two MM in component tab so I get one Purchase request respectively item 01 and 02 .

Now the Purchase request has been released and POs are created and did good receipt too.

(2) now later can i go to IW32 add third component as 03 item and Now PR has 03 appended and released?

What is a good practice needs to be followed to create a 03 request?

are all request should put it one shot or PM order is flexible to make request at any time to add more request.

Thanks for your suggestions.

Muthu