Complex sentence: Her cousin Nikki selects tacky bridesmaids dresses without Toula's permission; her brother Nick semi-jokingly threatens Ian that he'll kill him if he ever hurts Toula.
Split into simpler sentences: Her cousin Nikki selects garish bridesmaids dresses without Toula's permission. Her brother Nick semi-jokingly threatens Ian that he'll kill him if he ever hurts Toula.