I think sometimes it isn't about the stuff. It could be your Aunt and Uncle are doing the only thing they could think of to hold on. We're weird when we are stressed, we don't think right. Your relatives could have had a whole lot of time together growing up together, I assume. They could be reverting to behavior that started before you were born.
I think the best we can do is to be kind to everyone and try to overlook all but the worst, dangerous behavior.
I know about someone who, when he lost his parents, wanted everything that had to do with them. He said it was the weirdest thing. Go figure.
Concerning your grandmother, our body's chemistry is really complex. Remember how she has always usually been, that's her. You can laugh about this stuff. You have to, or else all you can do is cry.
Congratulations on passing your test. Welding is a skill that will serve you your whole life. I've always wanted to weld beautifully, but I never took the time to gain the skillset. Good for you.
I hope you and your family will be blessed with peace, and a new to you truck.