Hello Phoebe, your sister might want to ask her Rad On Dr about “magic mouthwash” it has lidocaine in it to help numb the mouth to help with eating. Some Drs call it Radiomix. It helped me a great deal.

Lip Cancer
Stage 3
T2 N0
Lip resection, reconstruction
Modified Neck Dissection
30 radiation treatments (last day 9/11)
Starting Physical Therapy on my neck
Barium Swallow Test after Thanksgiving
1st post op PET scan scheduled for beginning of December
Going thru it physically alone during the pandemic 2020