Stable Union visa? Recommend Visa Lawyer? (Rio de Janeiro)

Dear all - I am an Aussie with permanent residency who has recently returned to Brazil after a couple of years abroad and we are trying to figure out the best option for my boyfriend's visa (US citizen). As far as we understand we would be eligible for união estável because we have been together for more than a year and share finances but since he doesn't have CPF etc we have not been able to put apartment contract in both names or open joint bank account…so we have to get creative re documentation and "proof" of the relationship. Not sure if anyone has any advice based on your experience and/or recommendations of immigration lawyers or companies that offer these services cos I think we might need some professional help! Many thanks, Zoe