Ditto to the above. Regardles of the "real" problems, your sister IS going awefully far for "attention", even if that is the motive, and I'm not sure it is. Big problem is she is a lone parent, a small child is involved, and from your description, your sister makes quite a few bad judgement calls. I cannot and will not diagnose anything from here, but from your letter she needs to be dragged in to see someone as of yesterday!!!!
For her, and for the child. The kid's safety is not worth shrugging off your sister's behavior. Good luck to you and to your father, hon.