Visitor visa extension and Green Card

[bajaj75]

I have two question and appreicate if i get their answers -:

1. My parents are on B2 visa for 6 months and I am planning to extend their stay for another 6 months. I would like to know that if this visitor visa extension may create problems if and when I apply for their Green Card.

2. How frequently can my parents travel on B2 visa after their visit.

[immihelp]

1. No.
2. There is no rule regarding this. But if they try to spend most of their time in US, immigration officer at airport may deny entry as the intention is not tourism.