Two of my grandmother's brothers - James and William Bell - moved to Argentina about the time the rest of the family moved to Canada and USA (c. 18951885). I have correspondence between an agent of one of the brothers (James, I think), shortly before his death (early 1950s), and another branch of the family, asking if one of their nephews would be able to move to Buenos Aires and inherit his estate (the other brother had already died). No family member was able to qualify, and the estate was appropriated by the government.
One of their nephews had been able to visit them several times, as he worked in the maritime trades. He didn't speak Spanish, however, and was unable to determine whether either of the brothers was married (it would have scandalized the family if they had married native women, so they had incentive to conceal the fact). He noted that there were several children with names similar to 'Bell.' The agent mentioned above was named 'Bellucci' and described "Mr. James" as "like a grandfather to me."
How would one find information about these two and their lives in Argentina?