Hi Nikki,Maybe yes just in separate rooms where they'll be able to smell each other and your new kitty can get used to her surroundings and that she has a new sibling.Also maybe swap blankets,toys and after you've stroked one,stroke the other and then slowly allow them supervised short greetings and take things from their.Your older cat will be wanting to show younger kitt that she is top cat and intends to maintain her rank,and younger kitt will be just wanting to make friends,it may take a short while but they should settle down soon
Answered this on other thread too