My father doesn't talk to his siblings they are on bad terms. He doesn't want to see them anymore. When it comes to my wedding I wanted to invite them anyways because I don't want to severe my ties of kinship with them. Is this correct or shouldn't I invite them to avoid upsetting my parents?

Do not cut them. Shaykh Ibn Baz raḥimahullāh said the father is not obeyed in cutting ties over a worldly quarrel, and that you keep the ties, even discreetly if you fear things will worsen with him. As for the invitation, I would assume this is not cutting the ties, and maybe they understand the issue because you keep in touch with them and did not cut them off.