Hi Manas Rastogi,
I am not quite sure that I undesrtood your propblem correclty.
If the problem is that one item overlaps another, you can use the Canvas.ZIndex attached property to modify the ZIndex (z stacking) of an element. This property only works for elements that are children of one and the same element.
If want to drop the item in specific Grid Row/Column, then you can do two things:
1. Calculate where the element will fall and set the Grid.Row and Grid.Column properties. This will only work if you have simpler column / row definitions.
2. Place dummy items (like borders or rectangles) in the grid where you would like your items to go. Then you can use them for highlighting the drop are and on successful drop you only need to copy the Grid.Row / Grid.Column properties.
Hopefully this will work in your case,
All the best,
the Telerik team