Hello GaoDa,

A child born to Braziian parents in Spain, if the parents do not register the child at the Brazilian Civil Registry, will be considered of Spanish origins. Therefore, the baby will be able to obtain the Spanish nationality, and his parents could obtain a residence permit by Family Settlement in Spain ( applied for from Spain, pesonally ), as the parents of a Spansih citizen.

I am unaware of the British Law in this case, should my wish to settle in the UK, as we spacialze in Spanish Law. I recommend you to make an enquiry at a British Immigration Law forum to find the answers to your last question.

Regards,