My Brazilian mother-in-law is trying to get a tourist visa to visit my wife and I. She was denied two times in 2012, saying that her income was low

Since it is a matter of low income on your mother-in-law's side, you could perhaps alleviate the situation if you and your wife are earning a decent living in the country. In that case, you could extend an invitation for her and the son guaranteeing their expenses and that they will return to Brazil at the end of their period of visit. You can also attach Form I-134 affidavit of support with job letters, banking statements, and tax returns. Due to the limitations of the Lawyers.com Forums, Alan Lee, Esq.'s (the "Firm") participation in responding to questions posted herein does not constitute legal advice, nor legal representation of the person or entity posting a question. No Attorney/Client relationship is or shall be construed to be created hereby. The information provided herein by the Firm is general, and requires that the poster obtain specific legal advice from an attorney. The poster shall not rely upon the information provided herein as legal advice nor as the basis for making any decisions of legal consequence.