write on an excel file over the network that user only has read-only access to

Okay excel experts I got something tricky here for you guys, perhaps a toughy one:

I have an excel inventory.xls over the network with permission such as:

bob:all permissions
jacob: read-only

I have an excel enterToInventory.xls over the network with permission such as:

everyone: all permissions

What I want to do is have jacob open enterToInventory.xls and enter inventory data on that file. Once he submits data on that file I want to run a vba code that opens inventory.xls that gives jacob write permission and writes onto inventory.xls. Once done writing, jacob then loses the write permission and only has read only permission. Is this even possible? Help would be greatly appreciated.

Basically what I'm trying to do is to have everyone be able to enter data into the inventory.xls over the network but unable to edit it, except Bob (Bob is the document control guy who is the only one who should ever be able to edit anything in inventory.xls). All other users can only enter data into inventory using enterToInventory.xls. Since the inventory is "read-only" for everyone but Bob, 5 people (other than Bob) can view the inventory.xls while Jacob is writing data in it at the same time (of course the 5 people have to close and reopen inventory.xls before the written data is shown). If anyone knows a better method of this, and can avoid the read-only stuff let me know. Thanks!!!

maybe I'm oversimplifying, but couldn't you have some Vlookups in excel inventory.xls, looking into enterToInventory.xls? That way everyone can enter whatever they want into Enter, but only when you open and save excel inventory.xls would it be permanently saved.

Well I don't really want anyone messing with the inventory, so only I would have access to it, meaning I would have to open and close it each time to refresh and save it, which might be inefficient. Also enterToInventory isn't a log so im not sure how vlookup would work. If it were a log vlookup gets really slow eventually when there's a lot of lookups. I've been thinking of how to use vlookup also, but couldn't really find a way to use it unless i use vlookup with an event handler, like when something happens in another file vlookup and enter into inventory, but that seems like a poor approach.

You wouldn't necessarily have to open and close it all the time. Jacob has permission to save to enterToInventory.xls, so he can put in whatever changes he wants. Have 5, 10, 100, however many VLookups you think you'll need in inventory.xls until you can get to the file again. When you do eventually open it, you can decide what changes to keep or what to discard. Copy/Paste the VLookups as values, create a new set (all of this could be doen via VBA). So, at any time you'd have a limited # of VLookups. If you want to keep EVERYTHING that Jacob enters, it's even simpler; have Windows Scheduled Tasks open/close inventory.xls automatically each morning, and have the inventory.xls automatically convert formulas to values then creae X number of new vlookups.