It is always annoying trying to cope with difficult relatives. At times, the more you try to help them, the more it seems you are their real problem. At times, difficult relatives are not really difficult just that they tend always to have a strange point of view on most things.
One of the ways to cope with difficult relatives is not to make it look as if you want to fix them. Most of them don't like this approach; they won't appreciate anything you're doing for them. In fact, you might end up being their worst enemy. Just leave them with their nature and relationship with them that way. Try as much as possible not to enter into an argument with them. Whenever they are making their point, all you need to do is to be attentive and listen to them. At times when you do this, you will understand that they are not unnecessarily too difficult. Don't treat topics that will force you into an argument with them. The whole idea is to be neutral with them. With this, you'll get along very easily.
Some people are blessed with relatives who are always willing to help them in the various steps that they take. Then, some relatives are just difficult to deal with. How are you going to deal with relationships that are hard to be with? You have different options.
You may always choose to not meet up with them to avoid conflict. If you do have to meet up with them, you may try to listen to them and try to see what is causing them to become difficult. You can also try to explain your side, but there is a big chance that they will not listen to you anyway.