With so many people needed access to the sheet index file, having it single user access is not very workable. At the very least, allow users to each folder within the sheet index at the same time as a starting point. Ideally we would be able to have multiple users in any part of the sheet index at the same time, but I know that is hard to do when storing it on ProjectWise which most of us are. That is why i think breaking access out by folder may be a reasonable solution