Hi Judy,
I've been Dx'd with UC for ten years now, but believe I've had for 15+ years. I've gotten it under control using a mixture of traditional Rx meds., mainly Asacol, and vitamins, probiotics, and HUGE changes in my diet.
When buying vitamins and supplements make sure to check with your doctor are pharmacist to be sure nothing will have an adverse interaction with anything your daughter is taking prescription-wise. And, be sure to buy good quality products, preferably not made from products supplied by China - there just are no good regulations on supplements, vits., or Rx drugs on things coming out of that country.
You may want to read some of my Shareposts on this site about doing an Elimination diet (ED) to identify foods that might be making your daughter's symptoms worse. Doctors don't tend to put much weight into diet affecting IBD symptoms but there are plenty of us IBDers out there who find that diet is hugely important to keeping our guts happy and healthy.
Be diligent, but also be patient.
Good luck to you,
Elizabeth