B2 Visa for parents - Sponsorship Doubt

Hi,My mother intends to visit US to see my ‘expecting-sister’ & brother-in-law. I am thinking of getting visa for both my parents at once (while only my mom will visit US as of now)Details:- My sister is a home maker, while my brother-in-law works for a US firm- My mother (aged 62) is a home maker too, while my father works as a private lawyer (hence, no salary proof, no IT returns etc.)- Assets in their name: We have a house in my hometown in my mother’s name, land in my father & uncle’s name, 5-6 lacs of bank balance, plus some jewellery- Me: I am their son, working in India, earning very well (30+ lacs per annum). My wife is working too & we just had a kid - so, family dependency in India for them. Both my parents are kind of dependent on me.Now, I have following questions:- Can I sponsor their trip, i.e. their son in India?- If not, then what would be better - self-sponsorship or sponsorship by brother-in-law? Which would have better chances of getting the VISA?