I finished my PhD and will be on OPT from August 2012. I have job a short-term postdoctoral appointment in Purdue University from August 2012 to December. We (me and my family) went India in April 2011 for a family visit. Since our visa were expiring soon, we appeared for visa interview. My visa was granted, but my family's visa (F2) was denied under section 214(b) INA and Public Charge. Since that time, my family appeared two more times for visa (F2), but they could not get the visa.
Now, after graduating in Summer 2012, I would like to invite my spouse and my son to attend graduation ceremony in Fall 2012. For this purpose, I want to invite them on visitor (B2) visa. Please tell me the whether this would be a right step or not. My son is 9 years old, and is studying in a school in India. So, they can not stay for long time with me.