Sister acts: ‘Echoes’ and ‘Bad Sisters’ ride sibling mysteries into the stream

In an ideal sign of the peak-TV times, a single Friday brings a pair of secret series devoted to siblings and their unique provides, including one along with (sort-of) evil baby twins. “Echoes” starts with promise upon which it will not deliver, while “Bad Sisters” — too long, but satisfying at the end — plays such as the never-made third period of “Big Little Lies, ” in which the really “bad” person is the abusive husband who winds upward dead.Continue Reading