Adoption?? Is this a mistranslation? But his ex grandpa is saying he will have a grandson ...

I checked the raws, and the writer uses the words for son, grandson, and grandfather. However, I doubt they won't cut off his connection to his biological family. Seonguk will likely treat it more like a business transaction in order to swallow up the Samjeon conglomerate.

That sucks. I'm already unsatisfied with the new dad's screen time and now this ex father is showing up.