Bernie Madoff’s Ponzi scheme played out across the front pages of New York tabloids, but the deaths of his sister and brother-in-law may be more private thanks to a victims’ rights law in Florida. Sondra Wiener, the 87-year-old sister of Madoff, and husband Marvin Wiener, 90, were found dead Thursday at their Valencia Lakes home in Boynton Beach, about 60 miles north of Miami, the Palm Beach County Sheriff’s Office confirmed Sunday. Both suffered gunshot wounds and officials said the scene “appears to be a murder/suicide.” An official cause of death is pending an investigation by the medical e…