Can’t set additional field for shipping address

Just as it is possible to enable address field 2 for billing, I would like to enable a second complementary address line for shipping. I managed to create the custom field, but it always appears to the user at the end of the list. Even if as admin I manage to move it, the field is not reordered.

How to activate the second address line for shipping or be able to move a custom field to the intended order?

The page I need help with: [log in to see the link]