In episode 11 of 'A Gentleman's Dignity' aired on the 30th, Colin (played by Lee Jong Hyun) revealed his identity to the four men.
Colin went to visit lawyer Choi Yoon first. Colin knew Choi Yoon would not delight in his visit for he had been seen with Im Me-Ah-Ri (played by Yoon Jin Yi) and given him a bad impression, yet he went to seek legal advice.
Colin said to Choi Yoon, "I have two fathers. My real father doesn't know who I am. I only recently found out who he was. If I reveal my identity to him, will I receive his inheritance, or does he have to pass away first?"
This evening, Colin visited Kim Do Jin's (Jang Dong Gun) residence. Ironically, all four men were present at the time. Lee Jung Rok (Lee Jong Hyuk) had dropped by to discuss his divorce, and Choi Yoon and Im Tae San (Kim Soo Ro) had joined.
Source: Korea Portal