Hi Kushog;
Over the years I've introduced a few animals to the household some with little or no problems, and then there were times introduction didn't work at all. About 10 years ago I came across an introduction method that I use today, and I have found that it helps greatly. It is imperative for the 16-year-old cat that you take your time with the introduction because it will mean that she will have to relinquish some of her territorial rights to the newcomer, and if she has no other animals in the house that she deals with over territory rights this could be stressful for her. Taking the new kitten to the vet before you take it home to have a check for medical problems is a great idea, and it will give you a chance to pick the vet's mind for ideas as well.
I am enclosing a couple of websites that you can have a look at dealing with the introduction of a new kitten to the household. It goes into more detail on what to do than I can here. It's basically what I do, and I've had good success with it. It takes between 5 and 7 days to complete the introduction but it does keep the stress levels well down for the animals.
http://indoorpet.osu.edu/cats/feline...pets/index.cfm
http://pets.ca/cats/articles/getting-a-new-kitten-cat/
Wish you the best of luck with your adventure.