Marcus here has a sister born in 1859, so she's 31 I think. She's a spinster and she could have not finished Hogwarts for some reason!

Alternative, for assistant needs, I'm not sure in which industry you want her assisting but she could work for Marcus? He'd definitely have one to take care of the more mundane parts of the business, schedule one-on-one meetings with clients, put orders, take care of the logistics of Lytton events, take care of PR, etc.

IDK hit me up on Skype if you think something might work for you!