In vb.net windows application,i used sql server 2008 for database. For deployemnt and implementation process, we used currently the sql server is in the web.client have different locations and want to access application from any where. The problem is at some rural area the internet down time is high and user unable to do data entry job in the application.Then the requiremnt have changed to use local server for branches . after completing data entry work and they want to update to sql server in the web.during that process latest transactions changes from local server have to update in web server, mean time another branch local server will also update to server in web.and local servers have to get exchange data through web server.When user click update button, only todays transactions from local server should update to web server and from web server transactions or other another branch latest data that had already updated have to transfer from web server to local server. What are the possible ways to do this ? could you guide me for this situation?

Software/Hardware used:
Visual Studio 2008,Sql server 2008