Link the PM Sub order to superior order

Hi Expert,

My Client have requirement is that he needs to attached sub order to superior order, according to his experience its available in T Code IW40 in SAP ECC 4.7 version.

I know that how to create the Sub order by using T Code IW36.

But can you tell me that its really available in 4.7 or is there any other T code where we can attached Sub order to superior order in ECC 6.00.

Regards

Sandeep Yewle