First off I LOVE Jackson Galaxy! His site always has great information.

I have successfully integrated new cats to my house on multiple occasions. I find all cats are different as far as how long it takes to get them together. I keep the new comer restricted to one room. In your case I would probably use your daughters room so she can bound with her new friend as well as prepare the existing cat for the new comer.

Tell hubby it can be done. My cats are 16, 12, 10, 4 and 2 and all have been brought home at different times and integrated into the household.