What is the difference between "velho" and "antigo"? Does velho not work here?
Velho sounds a bit rude. Essa casa é velha could mean it is shabby, but if you say antigo it means only old.
Actually is pretty normal to use it in Brazil, so it shouldn't be considered wrong. The text should accept both versions, since it doesn't explain if it wants the rude or not rude one.
I concur with Paulo.
We only use "sobrenome velho" for a "former surname".
is it wrong to use apelido instead of sobrenome?
No, different to Spanish, apelido in Portuguese means nickname.
I believe apelido is the correct term in Portugal. Am I mistaken?
I have also heard so... It should be accepted.
No, you're right, apelido is also valid
I've seen sur name for last name before in Africa, they speak Portuguese in Mozambique it's just different in some ways. That's not common at all I'm guessing or is it non existent?