hi, i'm a cancer survivor, not a medical professional, but here is my take on this:

The neck dissections are a surgical procedure along the lymph system,done to assess whether the cancer has spread through the neck lymph system and/or to remove the cancerous node(s).

your signature says your sister has "N1" meaning 1 positive node. I am guessing that the medical team found this through some sort of imaging such as MRI. My non-medical guess is that because she is undergoing 2 types of cancer treatment - chemotherapy & radiation, they are not going the surgical route (at least not at this point).

It is a reasonable and good question to ask her medical team. I found it amazingly helpful to have my husband with me at all of my appointments, it is great to have someone to help listen and ask questions and to remember the answers! I don't know if anyone is going with her to her appoinments but it is very helpful. Also, I brought a composition notebook to each appointment & would write down info, it also helps to write down questions.
I hope this helps some, and good luck on her treatment!
michelle