Requirement:
The desire is to have the PO under the parent sub and items will be shipped to a designated location in a child subsidiary?
Solution:
Enable the Centralized Purchasing and Billing feature.
Here’s an example, created a Purchase Order for a Vendor under my Parent Subsidiary and added the target subsidiary (child) and location of that subsidiary:
Item Receipt:
The location is in the child subsidiary and so does the G/L impact is allocated to the subsidiary.
You can check these SuiteAnswers articles:
98231 | Centralized Purchasing and Billing
98232 | Centralized Purchase Orders