Multiple extensions of Parents B2 Visa

[aspireforusa]

I'm in US for 3+ years and I'm EAD right now. My I485 interview has happened in May 2019 and waiting for retrogression to finish and get my GC. I'm staying here with my spouse and 2 kids. And my parents both 75+ years are in India. I'm reaching out for your help on how can I extend my parents B2 visa while they are in US? I understand many may have done while they are in US for 1 time on health or personal grounds, however wanted to understand can we do it multiple times and will that impact my GC process or future sponsorship of my parents?