In your research you might disagree with something: a position taken by another researcher, the results of a paper or conclusions of a thesis.
Your examiners might disagree with a method you use, the way you interpret something, or your opinion on a topic they raise.
You might disagree with your examiners on something they think, or the way they view something you’ve done or the way they approach research.
And all of this is fine.
It’s fine to disagree but the person disagreeing has to say why.
“I disagree,” is not enough. Say why.
You would have to do this in your thesis to present your research well. To be able to engage with your examiners and their disagreements with your work in the viva you need to know why. If they don’t say initially, it’s fair for you to ask.
Ask why they disagree, if they do, and use that information to see how you can engage.
Are they making a fair point? Are they missing something? Are they simply expressing an opinion or comment? Once you know why you can respond well.