article doesn't say that Yoel was rebbe of Sighet:

Rabbi Chananyah Yom Tov Lipa Teitelbaum, author of Kedushas Yom Tov, was Rebbe in the town of Sighet. He had two sons: Rabbi Chaim Tzvi Teitelbaum and Rabbi Yoel Teitelbaum. Rabbi Chaim Tzvi, the oldest, succeeded his father as Rebbe of Sighet. Rabbi Joel (Yoel) Teitelbaum was Rabbi in a city called Krooli and later moved to Satmar where he became Rabbi and formed the community of Satmar.
 In short, what are you talking about?