Wow, I didn't know that having our dx not be taken seriously was so common. I thought that this was mostly my experience since I have a milder case, but I guess it's sadly much more prevalent.
Newtus, I'm sorry about your sister. What an incredibly insensitive thing to say! We know that you're not faking your illness.

Hopefully in time, she'll come around and see the truth. In the meantime, try to ignore her hurtful ignorance. She can't diagnose you (or not diagnose, as the case may be) simply because she is your sister and a T. I hide a lot from my family; perhaps you're the same way? She may know you less well than most strangers, because you try to present a healthy mask to keep your family from worrying too much...
Along those same lines, no, my grandma does not know about my psychosis, or sui thoughts, or any symptoms really. She just has the dx. She suffers from really intense anxiety, and there is a rule in our family that we tell her as little as she needs to know. Several years ago, my mom was dx'd with cancer. If my dad hadn't forced her to tell, grandma would have never found out! So I know that she really isn't in the best position to judge whether I'm bp or not.
Miner, I'm so sorry about your mom. Hopefully she'll soon see that you are her son, not a label. That bipolar doesn't make you violent. That story is just heartbreaking; I can't imagine how I'd feel if my mother expected me to kill her...