How do I sync a list on a site from a list on a subsite in SharePoint?

Question

Our group has a main site and a subsite dedicated to our projects. Each project has a project lead and a completion % associated with it. We have a list on the project site that goes to each project's dedicated subsite within the project site. I want to duplicate the list from the project site on the main site, where any changes or additions made to the project site list appears in the main site list as well including the project lead and completion %. How do I accomplish this?

Here is a simple example of the hierarchy:

• Main site - Project list derived from Project list below
  • Project Site - Project list
    • Project 1 Site
    • Project 2 Site
    • Project 3 Site

Answer 1

What you want to do is an approach similar to this one that I suggested in a previous question. Now, the question I linked is the reverse of your situation: that person wanted to copy information from the master site onto all of the child sites. But incorporating this in reverse will work just as well, we just need to flip the logic. Basically, instead of attaching these event handlers to the master site, we will attach them to your project list site, and the updates will be passed only to the Master Site instead of iterating across all of the subsites.

Answer 2

In addition to ccornet's post you need to create a workflow or an event handler on that list that will fire each time something happens to an item:

http://koenvosters.wordpress.com/2009/07/31/howto-create-an-event-handler-for-sharepointmoss-2007/