My daughter was like this. She has bladder urge issues where the sensation to wee doesn't occur until she is at busting point and then it is difficult to stop the wee from coming out.
Try to get her in to see a continence nurse or even a physio if possible. I know there is a chair tgat can be used that sends painless, electrical impulses through to the pelvic floor to strengthen them. What worked for my daughter was time and teaching her to strengthen her pelvic floor by telling her to use the muscles to stop herself from breaking wind. Good luck LS xx