Have or Has?, or both are correct here?

No, with "parents" you want a "have"; in both cases parents is the subject.
And BTW, I'd add "one" in the second sentence: his parents haven't one either.

EladioConsider these sentences. Some people around me think "have" is the only correct way. I think both are correct. Any help from you?: Bob hasn’t got a pool and neither have (HAS?) his parents. Bob hasn’t got a pool and his parents haven’t (HAS?) either. Thank you, Eladio

In both the sentences, 'parents' is the subject of the verb, which is plural in

the word parents is plural, so it's "parents have". He is singular, so it's "he has".

Is there some reason the two of you felt the need to answer a post that was correctly answered five years ago?

Take a look a the date of the post and whether the answer is already given before you put your time and talents into answering these questions.

Grammar Geek - nice that people are participating no matter how old it was. We are accumulating information that other people may find useful regardless.

Sorry, but I disagree. Repeating correct information given years ago doesn't ADD to knowledge. If this were a math forum and someone said "What is the square route of 16" six years ago and got the answer "4" would it add to anyone knowledge if people posted "4" five years later? Or even one a year for five years? My answer is no. The correct answer was clearly explained. There's no need to DELETE

Is it acceptable to comment on your post from a year ago?

It is square ROOT not ROUTE.