>I have a problem updating or making changes to an app when some user has it open.

There have been numerous posts about this subject. The general advice seems to be that the current application is stored on a server, but the application is run locally.

So, users run a local shell that first checks for a new version on the server, and if there is one, copies it locally, then runs it. This way you can update whenever and the user's get updates automatically the next time they get into the system.

HTH