Q. My ex has been diagnosed with bipolar disorder. It makes it very difficult to co-parent. Will the courts grant me full custody when the other parent has a diagnosis like that? What’s good ex-etiquette? A. Lots of people struggle with mental illness. If a parent is struggling and there is a question of primary custody, it’s the parent’s behavior that determines with whom the child will live, not the diagnosis. For example, if your co-parent has cancer, the diagnosis is certainly not a reason to adjust custody. But if the parent is so sick that they can’t take care of the child, that’s when a…