Enhance SOP Returns by changes to Copy Order & allow linking between SOP/POP for returns Merged

Steps to recreate:

enter order containing a standard item line fulfilled by direct delivery.
enter return and copy from the order.
note the copied order is missing lines that were set for direct delivery from supplier to customer.
desired behaviour: all lines are copied. the user is prompted how to fulfil items that were direct delivery. Option to return to the original supplier via POP Return would be desirable. Link between SOP and SOPReturn & link between SOPReturn & POPReturn would be desirable. workaround: enter returns manually

Whilst I appreciate add-on products would allow this; it's something users might expect since there is a 'copy order' function.