Husband and I rescued three kittens from an outbuilding of an old dairy farm we rented in California. I still have Silver, though Mister and Toby have passed on...
They were very small when we took them from the granary, possibly 6 weeks old. I did not bottle feed them, I started them on canned food and dry kitten food free choice. We had a young cat (our first rescue) named Inky who was just over a year old and he took to the babies right away. He would let them suckle on his tummy.
Sil and Toby suckled, but I never saw Mister do it. After a few weeks, we lost Inky to the road (and decided ALL kitties needed to be indoor only) and while Sil and Toby stopped the suckling behavior...Mister started up! However, he wanted to suckle fingers and as he grew, it became my thumb that he wanted.
He suckled my thumb all his eleven years. I learned to sleep with my hands covered or I'd wake to find him attached to my thumb. Usually, in the daytime he only wanted to suckle if company came over and he was nervous. It seemed to settle him and calm him down.
I would try to bottle feed kitten some KMR to give her the suckling reflex she feels she needs. However, I feel you have a 50/50 chance of her either growing out of this behavior or keeping it for life.
*I would also like to note that I bottle fed a fawn once, and while she sucked her bottle down quickly, after she finished, she would go over to hte Great Dane and suckle on his lips for about 10 minutes. I think the need to suckle is a very strong instinct for survival.
You should have seen the poor dog! He would see her coming and turn his head as far away from her as possible, but she'd just walk right over his legs to reach his lips. Then he'd stare at us as if to say: "WHY are you LETTING her do this to me?!"