From my own experience, the inheritance process down there is pretty much by the book, and they even make you prove that there are no illegitimate children- you have to get an affidavit signed by seven people, if I remember. Usually even the best of the families go by the book with this process, as they want to avoid scandal. Now, you may encounter the usual problems with Rentas Internas but that is another issue.
Now people do play little tricks: lets say you are selling a piece of property there may be two prices, one official and the one under the table, plus a hidden broker, maybe an astute family member, who is getting 5% commission plus the difference of the real price and his share. If you are not in top of things, you may get cheated this way. But we need more details: are you illegitimate? Out of the country? how were you cheated? Please let us know!