Looking through the guide on this website and other resources online, I feel pretty clear on what to expect here. I successfully petitioned for my wife and stepson 14 years using the help I got on this website. Now my mother-in-law is a citizen and wants to petition for one of her sons. He has a wife and 2 kids.
Just for clarity's sake I want to know if we/she just needs to fill out an I-130 for him, and that single petition can be used to include his wife and kids, or if we need to fill out separate I-130s for each member of his family, too.