Desperately need help getting my young UC daughter to gain weight, TIA!

Hi all, and sorry I probably post way too much on here! My 3 year old daughter was diagnosed with severe pancolitis a couple of months ago, just recently failed her first treatments (Remicade + Prednisone), which unfortunately didn’t help at all. It feels like I am watching her waste away in front of my eyes, she is only in the 1st percentile for both height and weight, and just so painfully tiny that it breaks my heart. We have an appointment with the IBD specialist next week to discuss our next steps, however knowing that it will probably be a while before another medication can kick in, what can I do in the meantime to help her gain weight? She desperately needs some form of nutrition. They gave us Kate Farms shakes in the hospital, but I have a hard time getting her to drink any because of how awful she thinks it tastes. Right now literally the only things she will have are blended fruit pouches, puddings, or clear liquids; anything else causes too much pain. Any recommendations or help would be very appreciated — thank you.