Well, he doesn't necessary have to adopt the MC to pass on the corporation. They can just become trusted business partners or the ex-dad can also become like a mentor or something similar. He can even just sell the corporation if he thinks the MC is worthy enough to surpass him.
Maybe the previous dad will offer the be a godfather to keep a close connection? If accepted it would be frowned upon or ruthless to cross your godfather…
I feel like the vice president/ the ex father is going to offer the mc to become his adopted son.. i dont know, im probably wrong ( ̄へ ̄)