We also discussed this issue at the finance committee. We discussed it for approximately 15 minutes and we came to the conclusion that it was the right wording. You are accompanied by the staff you need, whether it be party staff or not. I don't see why we would add anything else.
We should simply say “that each member be allowed to be accompanied.” You could be accompanied by whomsoever you choose, be it office staff or someone from your entourage, and that would be the case for in-camera meetings as well.
Anything we add will create limits and you will have to deal with them. If we state “party” and you want to bring an expert witness or someone else in who is not from your party, you will be limited. If we only use the word “staff” it is not a problem. It is as open as can be.