Regarding Ship to Organization and PO line type

In Purchase Order shipment lines, ship to organization is picked from Financial option.   Organization given in financial option is also item validation organization, So, normally it is the master inventory organization.

When user creates a new PO, master organization defaults in ship to organization in shipment line. User has to manually go and change the organization from master org to child org.

Is there any defaulting rules or workaround, so that child organization come defaults in  ship to organization in shipment line.

In PO lines. line type defaults from Purchasing option. User are having 5 different line types. So, if user wants to use other line type, they have to go and manually change the line type.