There are quite a few fields to fill in, and I can't make up my mind regarding how should the autocomplete functionality work. I found 2 or 3 other similar questions here, but they didn't help me with this case.
Please ignore UI flaws in the images below. This is the 0.1 alfa version. I'm currently focusing on the UX issues.
Autocomplete drop-down appears on Line1, Line2, City, Postal Code, Country, Abbreviation. User may also type in whatever he wants in each field.
When an item is selected in that dropdown, the rest of the fields should fill up (depending on which field has the content assist, e.g. Line 1 fills up everything else; City fills up Country and Abbreviation).
Question: Should selected proposals replaces values that already exist in the other fields? Wouldn't that be annoying/confusing for the user?