I did this on TS4 also, initially I set up a goal that my sims wanted to buy the biggest penthouse in San Myshuno for him and his children, he work in journalism(?) i think, and also write book afterwork, he was struggling to manage time for his children, sometime i let him take personal time off from the career to spend time with the children, and only wrote book when his children asleep. i didnt purchase any of the aspiration reward as i dont want the game to be easier. he completed the goal in 2 weeks(real time) just after his children aged up to young adult.
I dont know what was your goal with your sims and blair was, but it seems you also wanted to get them larger house from what i've read.