Like most people here, my first thought on NYZ's undercover job was as a courtesan (a female one at that! lol) but then I think back on how he feels about courtesans and females forced into that work... so I dunno. If not that, what else would have been so embarrassing to never be spoken of again?
I don't get why the daughter in laws in Asian dramas get such positions in the companies, enough to make decisions…
I can't say for other dramas, but here it seems logical. TH's mother died when he was young. His father probably also did. Stepmom looks to be a capable businesswoman + added power due to filial ties. Aunt doesn't look that smart to be part of the main business. It makes sense for her to be in a high position in the business. Grandpa hasn't really relinquished his hold over the business too. TH and even stepbro are younger, but just at the right age now to take over the business, hence stepmom's agitation and ruthless scheming.