Carla is spot on in my opinion. The multi-day vEEG's are great because you are much more likely to catch a seizure. Also they can try different things to try and stimulate a seizure if they wish. (And the patient agrees of course!). As Carla has said, they are not painful in any way... not much different to normal EEG's in that respect. The worst thing is probably getting the glue out of your hair at the end. It can be time consuming but done worry, your friend wont need to go bald! lol
I also agree with Carla and I too would like to suggest you encourage your friend to agree to the sleep deprived EEG. While she is in the hospital the staff will also be able to document her other problems and will observe first hand her difficulty in functioning.
I am so sorry to hear your friend is going through this but how lucky she is to have you as her support person and her friend.
Take care and keep posting.Kitt