You can’t reason someone out of something that they weren’t reasoned into in the first place. –Mark Twain
To improve the family interactions, you might start with a simple greeting card or meme indicating your openness. It is testing the water before a potentially difficult and volatile conversation. Or reach out with: ‘Can we talk?’ Use “I feel” statements. “When you exclude me, I feel hurt”. “When you no showed for my graduation, I felt let down.” “I wish we had a stronger connection.” You get the idea. Make sure your side of the street is clean – no accusations, no nastiness. Give them a chance to apologize, “make nice” or try to save face. Then take a breather and see where it goes. Kudos to the parent or sibling who listens openly. There is hope. If they dismiss your concerns and respond with denying, negative, discrediting, or toxic statements, pull back. They are not yet ready to change their long-standing point of view.