B1/B2 Visa Extension

[1blue1]

My parents are visiting USA on B1/B2 multi 1 year visa right now and they are staying 6 months.After, they are going back and would like to return in the USA probably right before their 1 year multi visa expire.
Is there any time frame to enter US again before their visa expire and get another 6 months stay?
Thank you.

[peace]

The two visits should be separated by 5-6 months if they are spending 5-6 months in US. The limit is not preset by law but is dictated by common sense and experiences at port of entry.

I suggest they stay 5 months in US on their first visit, return to India for 6 months and then can come again a month before the visa expiry. That way they will have a chance to get another 6 month stay.

My parents are visiting USA on B1/B2 multi 1 year visa right now and they are staying 6 months.After, they are going back and would like to return in the USA probably right before their 1 year multi visa expire.
Is there any time frame to enter US again before their visa expire and get another 6 months stay?
Thank you.