Bazzer40

My wife and I make regular trips to the USA to visit our son and daughter who have emigrated. We both have B1/B2 visa`s as we were advised to several years ago in case we needed to stay longer than ninety days. Lately we have been getting conflicting information from the entry immigration officers and on her current visit my wife was taken into an office and given an in depth interrogation before being granted entry.
One said we can only visit for up to six months in any one year, can that be three two month visits rather than one six month visit, and if so just when does the twelve month period begin? is it Jan 1st to 31 st Dec.
The second said we get a six month period from when he admits us even though we only stay for two months, and that a further six months would be granted at the beginning of each visit. Now we dont know what the rules are, any helpmon this one appreciated. Bazzer40