A This is a very common dilemma and it may be wise to reduce gradually the extent of contact and to change its nature over a period of time. However, you'll need to handle this sensitively. Not only will the girl be unlikely to want to relinquish the attention she is receiving, you will also need to be mindful of the feelings of the parents and the learning support assistant.
Some parents might become concerned that an attempt to reduce the degree of contact heralds a move on the part of the school or local education authority to make resource savings.
Your support assistant may become concerned seeing any moves on your part as implying criticism of her.
I would speak to the learning support assistant and ask her how you might both work together to reduce the child's dependence.
Once you are assured that you have agreed upon goals and strategy, speak to the parents about the course of action you propose to take, stressing that your ultimate aim is to help their daughter become more independent.
Try to ensure that the learning support assistant is not always immediately available whenever the child experiences difficulty, nor offers help too readily.
A useful notion is the scaffolding metaphor whereby only the minimal amount of assistance needed is provided. Too much help, and no learning results; too little, and the learner flails helplessly.
As the learner becomes more competent, the scaffolding should be gradually reduced until, ultimately, independent performance is achieved.
The other strategy is to vary the source of support so that one person is not identified as the solution to the child's problems. Sometimes, you might be the point of contact, freeing the learning support assistant to work elsewhere. You might also draw upon other helpers - for example, a Year 6 student - to assist in peer tuition. Research suggests that both tutors and tutees benefit from such participation.