Regarding the rumor of Joo Dan Tae and Oh Yoon Hee being siblings, an official from SBSŌĆÖ The Penthouse 3 confirmed that it is his sisterŌĆÖs name, Jun Hee, written on the script. On July 16th, the seventh episode revealed Joo Dan TaeŌĆÖs tragic past. Young Joo Dantae used to live with his mother and younger sister in a rundown area, waiting to be demolished for an urban renewal project, 27 Cheonsu District. However, despite JooŌĆÖs plea, Baek Joon KiŌĆÖs father (Nam Sung Jin) went ahead and tore down his place where his mother and sister were still asleep. Young Joo Dan Tae, who witnessed the death of his only family in front of his eyes, cried his heart out as he watched it collapse. Right after the show had finished airing its latest episode, the viewers pointed out the name that young Joo Dan Tae had cried out sounded like ŌĆ£Yoon HeeŌĆØ or ŌĆ£Jun Hee.ŌĆØ Some speculated that JooŌĆÖs younger sister might be Oh Yoon Hee (Yoo Jin). However, the production team clarified that the name was ŌĆ£Jun Hee,ŌĆØ not ŌĆ£Yoon Hee.ŌĆØ Nevertheless, as Kim Soon OK wrote the previous Penthouse series with numerous twists and shocking developments, viewers are continuing to speculate about the mysterious connection between Joo Dan Tae and Oh Yoon Hee. ┬Ā Source (1)

 The Penthouse 3   Are Joo Dan Tae and Oh Yoon Hee Siblings  - 47 The Penthouse 3   Are Joo Dan Tae and Oh Yoon Hee Siblings  - 77