Hi Kelly,
Ship To is available out of the box at header level in SAP variant, which, I believe, gets default from the Requester's profile. Though it can be customized accordingly to update the line level Ship To. To achieve this, you will have to write a trigger and custom action Java to update the line level Ship To upon setting/changing the header level Ship To.
Note : Header level Ship To is a part of Requisition while the line level Ship To is at ReqLineItem.
Thanks,
Sandeep Jain