Getting a kitten when I have a 14 y o cat? Can it work?

[follygirl]

My dd is desperate to have a kitten of her own. We already have a senior cat (14 y o) called Ally. Up until 18 months ago she shared the house with another cat who sadly had to be pts. So she has been used to sharing the house with another cat.
My mum regularly visits and brings her cocker spaniel into the house. Both dog and cat ignore each other and Ally will stand really close to the dog and give her superior looks. She is a very chilled cat who loves nothing more than going for a nap in the spare room.
Do you think it would be okay to get a kitten? I wouldn't want to upset Ally, particularly as she is such an elderly lady but my dd is absolutely desperate for her own kitten and I know that it would bring so much joy into her life. My dd does play with Ally but she isn't the most cuddly cat so their interaction is always short-lived.
I've read up on what to do when you introduce a kitten to a cat and as a SAHM I've got loads of time.
Have any of you done what I would like to do? Or am I worrying too much?

We got a kitten and we have a 13 year old. Both are males. The kitten is very dominant and chases our older cat. They hate each other. After a year they can sometimes tolerate each other. The children do get alot of pleasure from the kitten.

we had a 7 year old cat and introduced two 8 week old kittenns to him. He was not at all impressed but is a very grumpy, unsocialbe cat anyway! he spent about 2 weeks sleeping outside and only came in for food. He has never been a lap cat so it was not that unusual for him to be 'distant' but i was very upset and worreid that we had pissed him off beyond repiar. however, he got used to them adn they becamse realy good buddies. Unfortunately one of our kittens - maggie = went missing last November never to return and we rehomed another adult cat. We had the same scenario played out with Charlie becoming distant and allof but now they all get along just fine with only the occasinoal hiss from Charlie.