Hi.
Have you excluded renal stones?
Renal stones or no, maximum water intake would make her easy to solve UTI and dissolve stone to some extent.
If I were your physician, I had instructed you to resort to safe herbals like
Cystone syrup, Varunadi Kwath decoction and Neeri tablet acting to reduce infection of
urinary tract. Chandanasav syrup is of immense help when taken with Shubhra ( anhydrous alum powder) and stops blood in urine and burning micturition. If stone is there, pt. is given one or two additional medicines.
No surgery required, tendency to uti and stone formation is controlled and stones up to 5-7 mm easily expelled by dissolving sharp edges. Wounds healed in urinary tract. Most important is these have no side effects at all. No potassium loss. Totally safe and used worldwide.
After all you always have option for surgery, lithotrypsy and toxic antibiotics but these WILL NOT reverse the tendency to form stones or UTI. Yes these are a bit slow being natural.
Hope it assures you of this unexplored option and any Ayurveda doctor can help you in this.