I think Chad was the one to make DiMera legit. He created the legit enterprise when Stefano died because he wanted a real legacy for his kids. EJ was still dead if I remember. And Abigail helped her husband rebrand it in her capacity as a magical PR expert. Andre helped, kind of, until his shenanigans and Abigail’s mental issues got him murdered. Kate also helped.
That’s how I remember it, so it’s hilarious to me that Chad’s crooked relatives have pushed him out. Just like they stole Gabi’s company and act like she has no right to it. They also own Basic Black, which Brady built. None of the current CEOs in waiting (aside from Gabi) had anything to do with building the assets DiMera touts as a company. EJ acts like this is his baby. He was dead and then an angry mummy when the company was born and grew. Unless I’m not remembering correctly, the current corporation is more Chad’s creation even than Stefano’s.