We use MijoShop (opencart) and need to use two extra fields in the shipping address only. Both for checkout with account and as guest. The extra fields should also be sent in order emails.
We need the checkout modified accordingly (safe for Joomla and MijoShop updates).
Only bid on this if You have experience working with MijoShop (opencart) modifications that are non destructive. We have zero time for people "figuring things out" - You have to know exactly what You are doing and work quickly on a development site. You have to document exactly what is done, how the modification functions and what files/code is used/edited. We need to be able to replicate Your work on several sites.