So if i understand your needs, you want to be able to do the following things when you add a supplier order :
- define the delivery address to inform the supplier where to deliver products.
- print this delivery address on the supplier invoice.
is this right ?
in this case, you have to define a new external contact type in the dictionnary; give it the name “delivery address”.
Then you can define the delivery address on the contact/address tab of the supplier order.
All you have to do now is to update your pdf model to print this information on the supplier order document.
If you need help to update your pdf model, there are lots of small companies around dolibarr that can provide you this service at low cost 
Unless of course, someone helps you for free in the forum by giving you the modified code if it’s really easy.
