The biggest misconception when it comes to line calls in doubles is that people think that if partners don't know about a ball that the other partner called out, it casts doubt. That's not the way it works.
Partners DO NOT have to agree on a line call. They just CANNOT disagree on the line call.
If your partner calls it out, and you are sure it was out when asked by the opponent, tell them it was out. That should end the discussion.
If your partner calls it out, and you didn't see it either because you were not looking where it hit, or you were blocked by your partner, or your partner just had a better look at it then you, when you are asked by the opponents just tell them that your partner had a better look, or something like that. That does not justify the opponents claiming the point as partners not agreeing. Also, there is nothing in the rules that allows you to replay the point if you are unsure of a line call. It's either in or it's out. It's either your point, or their point.
If your partner calls it out, and you flat out saw it clearly good, it's your responsibility to overrule the partner's call. Then, you lose the point. You don't replay it.