Hi Srdjan,
Its funny I came across this post when I looking for a solution to event handling and I found your question about the grid controls. I struggled with the same situation for while before I tried the options below.
A bit of info before hand , I am new to Test Complete and currently working on a Windows based .NET application. Most part of my application uses similar data and a number of panels are grids. If you haven't found a solution already, please try this and let me know if it works.
Go to Tools Menu -> default project properties / current project properties -> Object Mapping -> Microsoft Controls (since the grids I am working on are System.Windows.Forms.DataGrid) -> check the derived classes check box -> and additionally Click on 'Add From Screen' button and map the grid of your application using the object finder -> again check the derived classes check box for the new object map. Save on close
Record an action on the grid after changing the settings and try to derive the child objects or grid properties.