The member items of a Kit/Package item type are in essence being sold as a group. Even if one Member Item is set as Drop Ship by default, it will still be grouped along with the other Member Items before it can be fulfilled as a Kit. There is no partial fulfillment on Member Items of a Kit in such a way that drop ship items are delivered directly to the customer.
Drop Ship Member Items of a Kit are treated by the system as if a Special Order Item. This means that items purchased will be delivered to the location specified in the transaction and not directly to the customer. Thus, the location that will appear in the Ship To field in the purchase order form is the address of the location set in both the sales order and the linked purchase order.