Responses
As the eldest son, ilyeon needs to have a child as heir for his family, and as a yin (omega) he has to be impregnated by a yang (alpha). Their relationship will be sex partners, then he will marry another woman as the formal wife. So maybe that's why Myojin (the broker) hides their identities, because the meeting purpose is just to make a baby that will be taken by ilyeon family. It's to prevent the yang (Eunsok) family from claiming the baby later on. CMIIW
Thank you for explaining! (づ￣ ³￣)づ
And why should they not know each other??