Sharing Linked Spreadsheets

I have three workbooks that contain references to each other. I'd like to share these with my accounting folks, but cannot solve the problem of how Excel references the links when the spreadsheets are not open at the same time.

Both PC's are Windows 7, so I am thinking there has to be a new solution for this old problem.

I'd put the files on a shared server, and map both computers to a shared drive, except that our servers are in the cloud and running Linux -- so no safe/easy way to have them appear as a shared drive.

I tried creating Libraries with the same name on both computers to no avail.

Problem is unless my accounting folks remember to open all the workbooks together, I get a phone call that they have errors in them.